One time key counts differ between /sync and /keys/upload

[matrixbot]

This issue has been migrated from #10766.

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Description

I noticed that after sending an encrypted in a large E2EE room (#e2ee-test:grin.hu) my key count responses got out of sync (might have happened earlier). On sync I got a count of 55, while when doing an empty key upload request returned a count of 33. Does synapse cache the key count for /sync somehow and that got out of sync?

After uploading some keys, the counts synchronized themselves to 50, so I am assuming the ones in /sync were wrong.

Steps to reproduce

• after sending some e2ee messages, check what an empty key upload response returns vs the count in /sync.

Version information

• Homeserver: neko.dev

If not matrix.org:

• Version: 1.42.0rc1

• Install method: ebuild

• Platform: Gentoo