Amazon Prime did indeed have Babylon 5 in 2018--the date those screenshots are listed. That was when I got into it. But I definitely remember it looking far better than it does on my ATV. Yes, the CGI is horrid dated, about like watching 'The Last Starfighter' these days...but it wasn't nearly as pixelated and slide-show style frame rate as it is now. I just hope it improves in Season 2 or 3. A lot of later seasons have more exterior battle scenes and it'd be a crying shame to have to see them look worse.
Right now it's like literally VHS quality. When it was on Amazon in 2018 it appeared more 720p. Now it's literally 480p--the same resolution of a VHS cassette.
I've tried the double-tapping the remote to zoom and it is worse than what I've been doing. My TV allows fine-tuning of the top/bottom/left/right width/height and that way it's not over-zooming or cropping anything, it's just doing what they tried to do with Bab 5, basically turning a 4:3 image to a 16:9 image.
But Babylon 5 already shows in 16:9 meaning I never have to muck with the aspect ratio. I can leave my ATV set at 4K and my TV set to 'normal' (TV won't allow adjustment when it's viewing 4K) and it still looks like a VHS cassette. The only show looking far worse is Saved by the Bell, which is SD and 4:3.
I don't mind letterboxing which is how widescreen pictures and movies are intended to be seen, but I literally cannot STAND 'Pillar-boxing' which makes my TV look more akin to a 25" console from the 1970s. If I wanted to view shows like that, I'd just lug in the Zenith...
I wonder if anyone makes 720p 65" TVs? at least then it won't be so jarring to view. I'll try your suggestions for match content being off, but there is no 4:2:2 option under Chroma, just 4:2:0 (where it's set now) and 4:4:4 which just makes my TV say 'no signal'.
BTW I just updated to tvOS 14.0.1 and both the password issue during purchase is finally fixed (the setting actually sticks like it should at 'never') and the HD tag and info part has returned to viewing when I click menu. Before it just went back or showed the subtitle settings. I've only so far decided to watch Stargate: Atlantis and Star Trek: Enterprise today, but even they look better than the same offerings on Hulu. Hulu's version felt SD as well, or at least, less than 1080p. I've also adjusted some settings on the TV for the color, contrast, sharpness, judder reduction/noise reduction as well as fine-tuned the zoomed in mode for aspect ratio to make it more 'correct' which has a noticeable visual improvement. At least for those two shows. I had my TV in 'game mode' for some reason, and forgot about it. Probably when I was last playing Fallout 4 on my PC connected to it.