New emails to some accounts appear as duplicates in the unified folder. I suspected it may be connected to the fact I use "All Mail" as the archive folder for a Gmail account, but now the problem is happening with a Proton account as well. When I restart Thunderbird, or deactivate and reactivate the Unified folders view, they no longer appear as duplicates.

I am using Thunderbird 149.0.2 on Windows 11. The issue started a few weeks ago. Any help would be much appreciated!