I learned it from another poster. I did the brightness trick when when I setup my fingerprintes (you setup four finger prints with the same finger, but with each fingerprint setup you change the brightness by %25 step. you start with the lowest brightness [assume it’s 0%] to the highest [%100] with each setup).

Thanks to that trick, I had at least %80 unlock success rate with my previous pixel 8P Pro!

I upgraded to the P9 Pro with the ultrasonic sensor, and unfortunately it’s actually worse than the optical for me, and add to that brightness trick doesn’t work with it either since it uses a different tech…