Having the exact same problem. I'm a new Mac convert and it's really frustrating. M1 Macbook Pro. Screensaver will just pop on....even though I have been actively using it. Have to close lid and open to get it back. Have noticed that it will still play audio and video behind the screensaver
I know it is no help...but I would suspect it is teething pains with the new M1 Macs. So much new...and in this case, likely the issue is with what has replaced the old
SMC. If so, it may take an update, or perhaps a firmware update to resolve.
On 10.15 and back you could try deleting the preference file(s) that holds sleep setting preferences (no worries, the OS would generate new default files). They live in this directory:
Macintosh HD/Library/
Preferences
The files are probably:
com.apple.PowerManagement.plist
com.apple.PowerManagement.[unique identifier number here].plist
com.apple.powerlogd.plist
Any .plist file is just a preference...they can be deleted safely in all versions of MacOS 10 to generate new default preferences. I don't have an M1 Mac with OS 11, so I can't say if preferences are any different now. If you want to view or edit a .plist file manually, it can be done via
command line, or, you can use any
text editor.
You can also move the .plist files out of the directory, and not delete them. New prefs will be generated once they are gone (moved or deleted), and you open and set the corresponding System Preferences.
This may help...but some functions are beyond preferences, so the only way to know (unless you find someone else that has) would be to try it.