I found where the email address that is adding +bounce to the email address is generated in the code now:
It is not adding it to the FROM field though. It’s adding it as the Return-Path header. This happens only when the Monitored Inbox Settings is enabled. So the quick fix for this is to disable this feature.
But this code was last changed 6 years ago. I don’t see any sign of this causing issues since the 4.3 version