Same bug here, MBA M1, first day of use, 50% of battery, multiple user accounts but only 1 active at the time (others were migrated in but haven't even been opened yet). Occurred while typing in Pages app in center of screen (so nothing to do with sleep time, touching hot corners, etc.) Pressing power key brings login screen back momentarily but it goes back to screen saver repeatedly... Eventually got back in after repeatedly trying the hold power to get login window and logging back in. System specs: MBAir M1, 2020, 8 cores, 16gb RAM, BigSur 11.1, Machine Firmware Version: 1002, Hardware Revision: 1 Cell Revision: 2735, System Firmware Version: 6723.61.3