Reposting new issue spawned from #6373

Issue reporter says:

I'm pretty sure this change (firebase 9.9.1) is causing infinite setTimeouts on reflect.app - we've just had to revert back to 9.9.0.

The 9.9.1 change is referring to the fix described in this comment:
#6373 (comment)

The PR that comment is referring to is:
#6439