Topic: SNES games when docked - picture awful

Hi there, new Switch user and really want it for the old SNES catalogue and to play docked however not sure if it's to do with the pixels etc but the SNES games in docked mode picture quality is awful and unplayable but no issue at all when out of the dock. Does this happen to everyone or can this be fixed?

Thank you

As to what SNES games are we talking? This is so General no one knows where to start?

Excellent thank you. I've tried two Donkey Kong Country games and the old Mario Kart and yeah playing on a 58 inch so think the TV is the problem
Thanks for your help