I haven’t seen anything like this either, though I have noticed that when I stop listening to music or a podcast that the lock screen controller seems to stay on there longer than it used to. It might be related to your notification bug. I’m running a Pixel 7 if that is anything to note.

Same. I’ve been using this set up for about a year. I was expecting it to be a bit clunky but it honestly feels more intuitive that my old Chromecast did.