I'm having exactly the same issue with my Ultra 3 and Airpods Pro3 (also using iPhone17 ProMax). I complained this to Apple and they assigned a rep who looked into this, did remote diagnosis and everything and then told me that this was a software issue and as such they won't conduct any repair, exchange, refund or anything and asked me to just wait until this gets resolved through software updates! Crazy. Have you had any luck since?