I'm searching a cause for the common display issue which occured to the most of the Samsung Flagships. I have a theory and I need some samples from the both victims and non-victims of this issue to confirm that.
I have attached a video showing how to get the sample from your device. What you have to do is, Take a screenshot at the very last step in the video and comment it with mentioning which device you have taken the screenshot. (Take the screenshot WITHOUT changing any options)
Ex: Galaxy Note 9 (SM-N960F) " Note: To get the device's model number from Settings --> About phone "
* Disclaimer - DO NOT use "Activity Launcher" app for other than taking screenshots. I'm not responsible for any action happens after changing any settings using this app. Better to uninstall this app after sending your sample *