My Q9FN was purchased in Septemer 2018. When playing movies the videos will regularly flash a split second of white sometimes black.
Similar to as described here: https://eu.community.samsung.com/t5/TV/Q7F-Judders-and-white-flashes
Also, a new development I am a gamer. After an hour or so sometimes sooner my TV will actually what seems to be a "reboot". The screen will go black, "SAMSUNG Q9FN" will display on the screen and then the screen will display my game with the TV's menu on the bottom. This happens every day now.
