backport action doesn't use bot account's fork

[Achllle]

When I manually run a backport, the resulting PR is made successfully in my fork. However when my backport Github Action backports, the resulting PR isn't made in the fork of the bot account whose PAT I use to run the action. Somehow the repoForkOwner is still set to the source repo's organization, even though the fork already exists in the bot account. I've tried both fine-grained tokens and generic PATs.

The .backportrc.json file in the repo's root has fork: true. I have not manually overridden repoForkOwner since multiple people in my team manually use the tool.