Perhaps something to do the image sensor being exposed the whole time during focusing on a mirrorless (and any other time the camera is active I guess) and a possibility bright light might damage the sensor? I'm sure I've seen claims that extended exposure to a light source such as the sun can damage a sensor. And I think I read something about Canon saying not to point the EOS R at the sun for too long ... although I just did a wick Google search now and couldn't find it so maybe I'm confused.Seems very random when it does. I've seen it a few times with fast primes, but then I also saw it the other day using a Tamron 24-70 2.8. Although, I was shooting towards the direction of the sun when it did this, so that's kind of understandable. I just sort of wonder why it's doing this.