Interestingly enough, a lot of what YouTube TV offers in the way of upgraded 4K content isn’t genuine 4K. Though it may be difficult to tell, most content coming out of the $10/month add-on is just 1080p content upscaled to 4K. It’s worth noting that upscaled content does look very good and has the ability to pass as native 4K nine times out of ten, however, it’s just not the same.
For instance, the World Cup 2022 in Qatar has had every match streamed via Fox Sports and its corresponding channels via YouTube TV. Fox Sports, of course, is included in the 4K Plus plan and offers the streams in that higher resolution. Unfortunately, that content appears to just be upscaled 1080p and not native 4k.