I had this issue on my new M3 too. It got much better after a couple of weeks, but I did log it with the SC. The pillar cameras seem very prone to condensation in the M3. It's not because of the dark. The cameras in my MX only get phased by heavy rain or fog.First, a few times I noticed an error message that the left door pillar camera is blocked. Then the right pillar camera. Then "multiple cameras are blocked or blinded". I searched this and found info on condensation and such but (if I'm looking at the correct camera - top side of the door pillar), the glass is clean and I see no condensation. I was driving at night. Anything I should check? Autopilot worked the 3x I tried it and the error doesn't seem to appear while using autopilot. In fact, the times I noticed it most was when using the left/right turn signals to make a turn.
Standard AP doesn't use the pillar cameras when driving along, but when you signal it checks the side cameras for cars in the next lane and warns you if not clear - hence why you would get a blocked/blinded camera warning when signalling. With FSD you get the blocked camera warnings more often as they are more active in FSD.