white flashes when recording on xs

ive just got a iphone xs in space grey 256gb

when i first got the phone i made the camera settings the best i could 4k at 60fps i then had a school play with my son and filmed it straight away while filming i notice the camera recording was really shaking really fast like there was no stabilisation i thought maybe it was the setting i then put it down to 30fps in 4k and hoped that would solve it . touch wood nothing has happened since but now i was filming my boy playing and the flash was on as it was on auto and all you see is white flashes flying across the screen i thought maybe it was as the telly and main room light were on so i went in a dark room and filmed and the same thing is happening . can someone shed some light on why this is doing this as to me there should be no reason for this . I've come from a iPhone 7 plus and never had a single issues