Room marked as unread when I was the last person to speak

[matrixbot]

This issue has been migrated from #14837.

---

Description

I have a room on matrix.org where the sync response shows me as the last person to send an event, but also has notification_count: 1. @gsouquet tells me that should never happen: if I sent the last event, the room should not be unread.

    "unread_notifications": {
          "notification_count": 1,
          "highlight_count": 0
    },

The room ID is !KCcFbqJHMQscdVsFTa:element.io

The URL I used to sync was: https://matrix-client.matrix.org/_matrix/client/r0/sync?filter=%7B%22room%22%3A%7B%22timeline%22%3A%7B%22unread_thread_notifications%22%3Atrue%2C%22limit%22%3A20%7D%2C%22state%22%3A%7B%22lazy_load_members%22%3Atrue%7D%7D%7D&timeout=0&_cacheBuster=1673621386081

My username is @andybalaam:matrix.org

The full sync response for this room is:

      "!KCcFbqJHMQscdVsFTa:element.io": {
        "timeline": {
          "events": [
            {
              "content": {
                "creator": "@lgian:element.io",
                "room_version": "9"
              },
              "origin_server_ts": 1669207170409,
              "sender": "@lgian:element.io",
              "state_key": "",
              "type": "m.room.create",
              "unsigned": {
                "age": 1651989
              },
              "event_id": "$T4yQFiEjK1NwvniRWmyjzdJQeJwSvz2TVh55BbPuhw8"
            },
            {
              "content": {
                "avatar_url": "mxc://element.io/079b96b843c4fe3f75712533f31233038d0d53d8",
                "displayname": "lgian",
                "membership": "join"
              },
              "origin_server_ts": 1669207170696,
              "sender": "@lgian:element.io",
              "state_key": "@lgian:element.io",
              "type": "m.room.member",
              "unsigned": {
                "age": 1651702
              },
              "event_id": "$STEseiYuCwtuJgj2nJH4_l2mq-b7aZJGMXefty9Yki4"
            },
            {
              "content": {
                "ban": 50,
                "events": {
                  "m.room.avatar": 50,
                  "m.room.canonical_alias": 50,
                  "m.room.encryption": 100,
                  "m.room.history_visibility": 100,
                  "m.room.name": 50,
                  "m.room.power_levels": 100,
                  "m.room.server_acl": 100,
                  "m.room.tombstone": 100
                },
                "events_default": 0,
                "historical": 100,
                "invite": 0,
                "kick": 50,
                "redact": 50,
                "state_default": 50,
                "users": {
                  "@andybalaam:matrix.org": 100,
                  "@lgian:element.io": 100
                },
                "users_default": 0
              },
              "origin_server_ts": 1669207170782,
              "sender": "@lgian:element.io",
              "state_key": "",
              "type": "m.room.power_levels",
              "unsigned": {
                "age": 1651616
              },
              "event_id": "$DoEVRqa-hHhg1GJdnlT7X_BPXgWpvv3ACp9akZ6pjc8"
            },
            {
              "content": {
                "join_rule": "invite"
              },
              "origin_server_ts": 1669207170814,
              "sender": "@lgian:element.io",
              "state_key": "",
              "type": "m.room.join_rules",
              "unsigned": {
                "age": 1651584
              },
              "event_id": "$5XX9KB-PNpUmp_zphOKtNVRdSiPPDwKO-zo1TWrsQDQ"
            },
            {
              "content": {
                "history_visibility": "shared"
              },
              "origin_server_ts": 1669207170820,
              "sender": "@lgian:element.io",
              "state_key": "",
              "type": "m.room.history_visibility",
              "unsigned": {
                "age": 1651578
              },
              "event_id": "$AoRJeIFLou1NpTPo8ydqXFV-5LyeXCDnT8NhJfot7nY"
            },
            {
              "content": {
                "guest_access": "can_join"
              },
              "origin_server_ts": 1669207170829,
              "sender": "@lgian:element.io",
              "state_key": "",
              "type": "m.room.guest_access",
              "unsigned": {
                "age": 1651569
              },
              "event_id": "$10LzQqIAeVJd6m5jbQ5iFZuIdUmNcCnj0k3-Yqkl6GE"
            },
            {
              "content": {
                "algorithm": "m.megolm.v1.aes-sha2"
              },
              "origin_server_ts": 1669207170837,
              "sender": "@lgian:element.io",
              "state_key": "",
              "type": "m.room.encryption",
              "unsigned": {
                "age": 1651561
              },
              "event_id": "$ZGp0VZGbACUCESNl8F7k2GM_w3umBFrhzPD17eR834Q"
            },
            {
              "content": {
                "avatar_url": "mxc://matrix.org/yqsMYtlqLZIlMOnqBRAXnkUm",
                "displayname": "andybalaam",
                "is_direct": true,
                "membership": "invite"
              },
              "origin_server_ts": 1669207171121,
              "sender": "@lgian:element.io",
              "state_key": "@andybalaam:matrix.org",
              "type": "m.room.member",
              "unsigned": {
                "age": 22
              },
              "event_id": "$rWoSNtthPJ1WHmoO_qqvX-Q-Jmy9dTqKfKZFTw4idPg"
            },
            {
              "content": {
                "algorithm": "m.megolm.v1.aes-sha2",
                "ciphertext": "AwgAEuABEy11curBDRBMoSJ7GLUujtDjycv2JXuIIqTrWNwVZr3tW4/YKBxUcD1SnBmffgoHDFlo9dTq03YAjg/sv2r/rcVb1xBwTJejQdOyVmL/QdLPLSWj3vgFWpA+jw1bV57sYyfawONZ5+hfemlZLClOjxZgD/IZ2/PmXlbStamj2uXbo2MrUiA4y/VhLCzvXZIeh5gs7WdxZXoanh0l9TAFISZtSr4GO60xL6GrbZ/oXf63WtDjZQ293eGr7xDMaMoF2qRycimZGQ3FX1+2N/peOM+p0PM0cgekP0rSqcLuRg3pq+dtF8guo9T/IhTIny25SmOSvmawc6pqXRO5WQI4hyfpNEmWLKTO9z/zU6nUGsDZMJMLFNnlGEwjpHZGO4ogQ1tyK8KWcQc",
                "device_id": "RJPFIRDZYD",
                "sender_key": "HlpwBwe9UsFhQ+WO7nJHI1CwjeXxPOOVCXE7zgzbCGg",
                "session_id": "gAQxX0A0RM2b+up0ibRb68u0gEm8pDQgrtw9w9F9hCo"
              },
              "origin_server_ts": 1669207174410,
              "sender": "@lgian:element.io",
              "type": "m.room.encrypted",
              "unsigned": {
                "age": 1648859
              },
              "event_id": "$MK3coNBUiKdbiwJbX3BZnYQsRFJE2DE5K7LSy5RBfYg"
            },
            {
              "content": {
                "algorithm": "m.megolm.v1.aes-sha2",
                "ciphertext": "AwgBEqABuFUjuZZaYZ0sd4tKqwZ3KBI1ULzLvINFHtPF053Bh8QqGDTx/Tgn6t5MFY/R1Oa7j1jNz6o5nH2kvj/30J5/w2e+R2ieZzjGhxzW1WsSu7DY+QTNipH4euorYp2R0BdawL+UHElQYZoYMg4ytVY+1fJRSF0aTPlXUjy4Wd1ZS9uzV9GtqMx4ImFtXmOeQSTUNEvllOEZxI4BAS5vuJt6HYrcLtuld7jiZlnvHHc8zuKLKqorMP06vuu4Bwx3OSy2zg5gf4ruXcAbP/jIv0mADpr2EK/Ez/eOmPlnKiDmCUUK6dfmNSnkAQ",
                "device_id": "RJPFIRDZYD",
                "sender_key": "HlpwBwe9UsFhQ+WO7nJHI1CwjeXxPOOVCXE7zgzbCGg",
                "session_id": "gAQxX0A0RM2b+up0ibRb68u0gEm8pDQgrtw9w9F9hCo"
              },
              "origin_server_ts": 1669207397906,
              "sender": "@lgian:element.io",
              "type": "m.room.encrypted",
              "unsigned": {
                "age": 1425363
              },
              "event_id": "$XO_0WwJAi40qcMUdOFqB4xvdY1mQP7jjdiKPKIkdS9k"
            },
            {
              "content": {
                "avatar_url": "mxc://matrix.org/yqsMYtlqLZIlMOnqBRAXnkUm",
                "displayname": "andybalaam",
                "membership": "join"
              },
              "origin_server_ts": 1669208822225,
              "sender": "@andybalaam:matrix.org",
              "state_key": "@andybalaam:matrix.org",
              "type": "m.room.member",
              "unsigned": {
                "age": 3,
                "replaces_state": "$rWoSNtthPJ1WHmoO_qqvX-Q-Jmy9dTqKfKZFTw4idPg",
                "prev_content": {
                  "avatar_url": "mxc://matrix.org/yqsMYtlqLZIlMOnqBRAXnkUm",
                  "displayname": "andybalaam",
                  "is_direct": true,
                  "membership": "invite"
                },
                "prev_sender": "@lgian:element.io"
              },
              "event_id": "$Wk2qUVwqsb8ive4l75sISoivifuXdm1l3iGEODpmm1s"
            },
            {
              "content": {
                "algorithm": "m.megolm.v1.aes-sha2",
                "ciphertext": "AwgAEqABvDb35eiTzLREumzMNc9nezQNMwKRlh9r9nHaPg8F4EBrVh6YIp+lgEpzhuUHYqCDIVF0j9jRZ693IsUxemQnN4cJbwGo/1GAqFovLZNXV6Q7MYxukgtPiVnyFNsYnd8yGHG90TiGRO5Wl8BJQ+gzqRqKjt6Ums3c8iNeSDmmwYrYxA+LcRGVTaFiey+ixg49XQ+R8Y8msVFnNzF1e48F/ZKBNs+ToaA3ks0younKFNIK0UEV0/z/evDcBsSqUf9W/23u/9RodXEswHHhUS6eE44HC9iOi7m6LZBt0YFMWfteBsE9gxMSDw",
                "device_id": "MKBDKTQJQJ",
                "sender_key": "Ss6eaJGA82Uc9TQn1BbcLqpm6jtjGGwqMBadf/8Y+WY",
                "session_id": "8RV7u4xrlnPO5yvqZpx/aqiHbq3+KTTYg193IpzzFPY"
              },
              "origin_server_ts": 1669208839345,
              "sender": "@andybalaam:matrix.org",
              "type": "m.room.encrypted",
              "unsigned": {
                "age": 4412625253
              },
              "event_id": "$dER5V1RCMxzAhHXQJoMjqyuoxpPtK2X6hCb9T8Jg2wU"
            }
          ],
          "prev_batch": "s3615474541_757284974_4801760_1841502201_1869275239_3913936_731927069_6351869257_0",
          "limited": false
        },
        "state": {
          "events": []
        },
        "account_data": {
          "events": [
            {
              "type": "m.fully_read",
              "content": {
                "event_id": "$dER5V1RCMxzAhHXQJoMjqyuoxpPtK2X6hCb9T8Jg2wU"
              }
            }
          ]
        },
        "ephemeral": {
          "events": [
            {
              "type": "m.receipt",
              "content": {
                "$XO_0WwJAi40qcMUdOFqB4xvdY1mQP7jjdiKPKIkdS9k": {
                  "m.read": {
                    "@andybalaam:matrix.org": {
                      "ts": 1669208824249
                    }
                  },
                  "m.read.private": {
                    "@andybalaam:matrix.org": {
                      "ts": 1669208824233
                    }
                  }
                },
                "$dER5V1RCMxzAhHXQJoMjqyuoxpPtK2X6hCb9T8Jg2wU": {
                  "m.read": {
                    "@lgian:element.io": {
                      "ts": 1669208845306
                    }
                  }
                }
              }
            }
          ]
        },
        "unread_notifications": {
          "notification_count": 1,
          "highlight_count": 0
        },
        "summary": {
          "m.joined_member_count": 2,
          "m.invited_member_count": 0,
          "m.heroes": [
            "@lgian:element.io"
          ]
        }
      },

Steps to reproduce

.

Homeserver

matrix.org

Synapse Version

{"server_version":"1.75.0rc1 (b=matrix-org-hotfixes,6a185c8b17)","python_version":"3.8.12"}

Installation Method

I don't know

Database

.

Workers

Multiple workers

Platform

.

Configuration

.

Relevant log output

.

Anything else that would be useful to know?

.