I've had a random annoying bug where a mysterious window with no controls and no menu bar presence appears on top of all of my apps with seemingly no origin, rhyme, or reason, and I can't do anything to get rid of it except restart. It looks suspiciously like one of the "do you want to allow this accessory to connect" dialog boxes but it doesn't have any text. It's really mystifying.

I hoped this update would've made my Mac more stable from the last release, and while maybe the performance is better, I feel like issues like this do randomly occur.