Apparently I got 20.4.1 a few days ago, but haven't been watching much TV so I didn't notice that essentially every channel was getting not authorized, V5something, or no signal errors. Nothing recorded for those last few days.
I just rebooted the TiVo again, and everything seems to be coming in fine after the new reboot. I hope it doesn't decay over time :-).
P.S. I did sign up for the priority updates once I saw it is supposed to fix the overlapping recording problem, so I guess this is the priority update finally making it to my system.