A growing number of user reports online suggest some of Apple's M1 Mac models are susceptible to a Fast User Switching bug that spontaneously activates the screensaver and leaves the user unable to dismiss it.
In macOS Big Sur, Fast User Switching allows users to quickly switch between user accounts without having to completely log out. Based on posts in the MacRumors forums, Apple Community forums, and on Reddit, however, a screensaver can sometimes take over the screen of Apple Silicon Macs without notice, rendering the desktop workspace completely unavailable.
While the screensaver appears on the screen, the mouse pointer is still on top and moving, but nothing else works, and users have to close and re-open the lid on their MacBook Air or MacBook Pro, or light press the Power/Touch ID key or use the Alt-Command-Q key combination to get back to the login page.
MacRumors forum member drmacnut:
Brand new Mac mini M1, 2nd day using it, Big Sur macOS 11.1 (20C69) with screensaver and screen sleep set to 20 mins. I was actively editing some Calendar entries when all of a sudden the same exact thing happened (screensaver on, user locked out). I ended up using Remote Access from my MBP to get in and log out the user on the Mini. The Mac mini then jumped to the login screen and it's working fine again now. Very weird.
Apple Community forums member Squeaks2369:
I am experiencing the same issue. M1 MacBook Air. Big Sur 11.0.1. Happens on two separate user accounts, both with the screensaver disabled. No way to exit the screensaver but to close then open the lid. Happens a few times a day while actively using the computer. Browsing various forums it appears others are having this issue as well.
Disabling Fast User Switching prevents the issue from happening, but that obviously leaves the login feature inaccessible. Having the screensaver disabled in System Preferences for all users doesn't seem to make a difference either.
The issue has been reported on M1 MacBook Air, M1 13-inch MacBook Pro, and M1 Mac mini models, and occurs on all versions of macOS Big Sur, including the latest 11.1 update. Affected users are advised to submit feedback to Apple to hopefully facilitate a fix.
(Thanks, Chris!)
Top Rated Comments
You will see your mouse pointer when you move it around (it's not supposed to) and few things short of Cmd + Opt + Shift + Esc will work. You can also use mouse gestures like trigger Exposé, which is really weird. During the Big Sur beta, this used to happen fairly often with no obvious cause.
My best assessment of the issue is that usually, another app will steal the focus. Something like the crash report window for some other program that crashed in the background will steal the focus by being put up to front. It's quite possible that fast user switching triggers this loss of focus more often, but I don't think this is either specific to M1 or Big Sur.
Hopefully they will start looking into this !
We had on the 16” mbp also for some weeks now
So if this is not fixed on software level..you will get this with m2 or m30 as well