I've had the following issues with my M1 Mini:
1) Sleep doesn't work as expected - assuming the light on the Mini should change in brightness when it's sleeping. The screens turn off but the Mini's LED stays lit at a constant brightness. However, there is a slight noise from the attached speakers when I wake the screen, which might indicate that it had disconnected and reconnected to the audio interface the speakers are connected to.
2) Safari has crashed a couple of times in the last 4 days. I think this happened during or after a sleep event (which may have failed) but it's a bit concerning because I do a lot of work in web-based documents.
3) I use a Dell D6000 dock with DisplayLink into which 2 x 1080p monitors are connected. I've had several issues with this.
i) where the screens weren't visible at all (after a reboot). Unplugging and plugging in the dock a couple of times fixed the issue
ii) Similar story with the Rode AI-1 audio interface. Doesn't always return after waking from a dark screen. Again, unplugging the dock twice fixes it (once is not enough!)
iii) I had a bizarre problem where I couldn't move my cursor to the 2nd screen, where the login prompt was located, even though I could move off the first screen into some "invisible" space. Again, reconnecting the dock fixed it.
iv) similar issue with an invisible window that couldn't be found or moved to a visible screen, and a browser window that got stuck on one side of the screen and couldn't be moved.
So most of the issues are dock related, which is an inconvenience but not a show-stopper. It does mean I have to position the Mini where I can easily unplug the dock though, so it is not ideal ergonomically.