That is incredibly strange. Firstly, it's unlikely to be an issue within a specific app as it's clearly affecting the nav bar and notification bar too, which aren't rendered by the app. However, an app could be doing something it shouldn't which is causing this. Secondly, and this is particularly odd, it's showing up in a screenshot that you took on the device. This rules out the screen itself or the connection to the screen being the issue. I'm not exactly sure at what point in the pipeline a screenshot takes place but I'm guessing it's just the raw frame buffer, and if so that could potentially indicate a hardware issue with your GPU.
I know doing this is really annoying and not ideal, but have you tried a factory reset? That would help to rule out a software issue. If you do a factory reset, don't pull all of your apps back over with smart switch as it's possible there's some dodgy old software (whether malicious or just incompatible) cauisng the issue. Personally I would do the following:
- Contact Samsung support explaining the issue and include the screenshot. This will get the process going and save time if it turns out you do need to return the device
- If you'd rather avoid a factory reset, you could try looking at all the apps you have installed and look out for anything weird. If you find anything that shouldn't be there or that you don't use, uninstall it. Also check for any firmware updates.
- Restart the phone. If that works, great, otherwise you'll have to try factory reset so:
- Backup your device if possible (I'm guessing you can do that with Smart Switch?)
- Factory reset the phone
- Manually install any apps you know you want to use from Google Play store
- Do whatever you normally do to replicate the issue - so I guess sign into Facebook and watch some videos
- If the issue doesn't occur any more, it was a software issue. Carefully look through the apps you want and install them. If the issue still occurs it's almost definitely a hardware issue.
