Can't say without testing phone. It may be a display issue or possible that screen card did not applied well. Can't say perfect reason on the base of photo only. Contact samsung care. They will assist you well. For now you can remove screen card & Just take a screen shot and check. If it don't appear in screenshot means it is a hardware issue.
Kindly complaint to Samsung customer support through Samsung Members App as error report also send log files Along with this error report for this issue and go to service center for check and resolves this issue. If you like please accept as a solution it's help to others users also, click on 3dots in my reply section and click on accept solution. Thanks.
