There is no question that Apple released a winner with the new M1 Macs. Despite using the same old physical design, the excellent battery life (in the laptops) and “shockingly” fast M1 chip earned them overwhelmingly positive reviews from critics and users alike.
As great as the M1 Macs perform, some users have reported a strange bug they are having a hard time explaining. It seems that sometimes the screensaver will override the operation of the computer for no apparent reason. There is also at least one instance of the bug occurring on an Intel MacBook Pro.
Users on Reddit and MacRumors’ forums say that the screensaver will activate even when disabled. Furthermore, once it starts, there is no way to exit it except by either shutting and reopening the laptop’s lid or switching to a secondary account and then back.
I have not encountered the exact issue with my 2018 Intel MacBook Pro, but I did notice that after installing Big Sur, the screensaver would activate even though I had previously had it set to “never.” Checking the preferences menu showed that the install seemed to have reset that particular setting. After disabling it again, I found the screensaver was still triggering after about 20 minutes. I switched to my secondary account and disabled the screensaver on it as well. Having it disabled on both user profiles solved the problem.
Several complaints mentioned having more than one user account on their device. MacRumors suspects it might be related to Big Sur’s Fast User Switching feature. I would have to agree. It might be that the screensaver activates on the secondary even if the primary profile is the one that is active.
Apple has not commented on the bug, but reports on the support forum have begun surfacing. It will likely not take long for Cupertino engineers to look into the situation. In the meantime, if you encounter the problem, check to be sure the screensaver is turned off on all user accounts. That might solve the issue until a patch comes along.