Pixelation during sports

I have both a wireless box and a regular box.  Both have recently been replaced.

Usually on the weekends when we are watching sports, the picture is so pixelated that we are unable to watch TV. Channels such as HGTV and FoosNetwork work just fine.

We did a trial of YouTube TV and were able to watch all the football games with no problems.  Now that the games are all done, we switched back to xfinity and of course we have no issues with any of the channels.

We have a technician coming out this week but I don’t think he’ll find any issues since there won’t be any sports games televised.

Also, we streamed a game on the xfinity app from my phone and air played it on our TV and it was fine. I don’t think this is a solution to the problem.

Is there something that we’re missing?  It’s really annoying and frustrating to not be able to watch sports on TV. Right now, we’re seriously considering switching to YouTube TV.