hi bro, thats not good. did you check with apple service center once? even though its not the green screen issue some users were facing with 13 pro and pro max models as I mentioned in our recent video. do run diagnosis once with apple service center. no other users from our audience reported about flickering issue so far. problem could be specific to your device.
Do check and let me know bro. then we can contact apple support if there is any defect found by the technician.