PSE 2020 Update - (20201207.m.154403)

I was just using my Editor to edit an old photo. When I closed the Editor an Update notice popped up. This seemed a little odd to get an update for PSE 2020 several months after 2021 was released, but I clicked OK to proceed. The update took about 7 or 8 minutes to finish.

Now both my Editor and Organizer are updated to version 20201207.m.154403. I don't remember what the version numbers were prior to this update, but they were different, and my Editor and Organizer had different version numbers.

What's been changed or updated?