In 4:2:2 subsampling (or lower), information is lost. It’s not much information, but if I’m streaming 1280x800 or 1280x720, each pixel is partial defined by the ones around it.

If I stream 2560x1440, when reduced to 1280x720 each pixel is the combination of those 4 subsampled pixels. Meaning each individual pixel is independent from its neighbors.

It doesn’t sound like it should mean much, and maybe I’m wrong entirely about the reason for the lower detail when streaming 1280x800, but the difference was apparent to me (at least when I tested it with Cyberpunk 2077). I could very well be wrong, I’m not an expert. There could be other causes. But either way streaming at 1440p looks better on the 1280x800 screen than streaming 1280x800. (Except with 1440p the aspect ratio means small black bars at top and bottom).

Now that I think about it, I might be able to turn off the subsampling in the stream. Might be a good way to test it if I can.