Is this a 720p TV?
Check the display format of your TV. There are usually several settings that you can toggle using a button on the remote control: 16x9, Stretch, Zoom, Wide... etc.
I've been seeing this as well. It might be a weird bug.
Because it's garbage? Tried to run it with plutotv and it gave me nothing but headaches so I gave up on it. I mostly use kodi for my streaming needs now.
Anyone else seeing this? Running nexus player and using hd homerun tuner.