Now I’ve found a problem. Similar to what I experienced with 11.6.1 (and reported in macOS Big Sur 11.6.1 and Security Update 2021-007 Catalina - #19 by Will_M), Time Machine is no longer completing backups, either on a Time Capsule or an external (spinning) drive. My recollection is that many days or weeks later, Time Machine just started working again, but maybe it was when I upgraded to 11.6.2.