I'm getting this error in the error console for every single folder being auto archived (no matter if there is any mails to archive or not).
Error: Support deprecated since Thunderbird 121 and removed in Manifest V3: messages.list() requires to specify a MailFolderId instead of a full MailFolder object. background.js:769
searchMessagesToArchive moz-extension://3d326eaa-ddab-42f5-a8ba-3ac6f7503a90/background.js:769
Auto archiving does seem to work anyway.