MirrorMeister screen mirroring app shows exactly what is displayed on the screen of your phone. Each iPhone and iPad models have different aspect ratios and they aren’t always equal to TV screens – TV screens have most of the time a 16:9 aspect ratio.
For example, the iPhone 10 and 11 have a 19.5:9. aspect ratio. iPad models, on the order hand, can have screens varying from 4:3 to a wider 4.3:3 or 12.9:9 aspect ratio. And this is the reason why black bars can appear on your TV screen during mirroring.
However, some devices (like the iPhone 10 and 11) let you manually enlarge the screen for a better view.
You can do this pinching and zooming your screen or enabling a full-width screen option if the app you are mirroring supports this feature.
Did this answer your image in full screen question? If not, please do contact MirrorMeister customer support.