I haven't encountered this with 5.9 kernel at all. However, I've did run into it few times with 5.10.1 and haven't seen it so far with 5.10.3 (few days). Its really weird as it was almost 50/50 chance of getting that error at boot, one day but not the other (even with 5.10.1). I think we probably can close this as I can't reproduce it.