Who I have the same questioned this topic

I'm using a Fios TV One box and turned on closed captioning, which looks surprisingly terrible on my 4K TV? Blurry, stretched...

When viewing Netflix or anything on Apple TV, the captions are sharp and perfectly legible. Why the major difference on the fios box? I've tried several setting combinations and didn't  get results.

Has anybody else run into this issue? Were you able to fix it?