It depends how close you sit to your TV and how large the TV is. I can tell a difference if I’m close enough or if the screen is large enough. As well, try turning on a streamed 1080p show and using a 4k bluray (if you have all of thrsr things). When you stand close (like, closer than you’d watch), you can really see the difference. As you back away, it becomes less noticeable, but even at comfortable viewing distances people can see the difference

You can see an example on your phone. Try watching a video in 1080p and then 480p. You should notice a difference, even if you hold your phone a foot from your face it’s the same idea when watching on a tv.

The two big problems for me are (1) increased slowness and lag, and (2) phantom notifications (a red 10 dot in the bottom notifications but I click in and see that it’s empty)