Even if it's 120 fps you can still have high latencies, because the time from button press to the next frame acting on that button press can be slow. The game

Even if it's 120 fps you can still have high latencies, because the time from button press to the next frame acting on that button press can be slow. The game can stream at 120fps, but take extra like to register a jump for example. Again, you might just not be sensitive to that. There's also compression artifacts and bitrate that can make fine details already coarse and all that, even if it's 4k. That's what some won't find to be an issue and others will.