Black spots sporadically appear
All I have recently had black spots sporadically appear and disappear on my iPhone 7 Plus. When recording the screen these spots still show up, is this likely to be a software error? Or a hardware error? The dots appear and move while the screen is being navigated and then they disappear. Any help appreciated. Please see first photo at the bottom and second photo down the right hand side.
iPhone 7 Plus, iOS 13