Thunderbird thinks every message is Junk

I’m using Thunderbird 91.9.0 (64-bit) on Manjaro XFCE. This problem may have started with an earlier release of Thunderbird, but the problem is that Thunderbird puts a banner on almost every message that says “Thunderbird thinks this message is junk”. I have to manually click the “Not Junk” button to view the complete contents. This happens for senders and mailing lists I’ve been receiving messages from for years. What is going on here? Is anyone else seeing this behavior?

Review your Junk Settings in each of your mail accounts under Preferences. If your configuration is very basic, try with a clean profile. I would backup your current profile beforehand, just in case.

My filters are stored within the config, in each email account in a file called, msgFilterRules.dat

Thunderbird isn’t learning. It just marked as Junk email from a sender I already told it isn’t junk. The file msgFilterRules.dat only has one entry. I’m going to turn off Adaptive Junk Mail Filtering and see if that helps. The weird thing is that this just started happening recently, and I’ve been using Thunderbird for years with no changes to settings.