Speaking as someone who spent a lot of time in front of CRTs, this is NOT what an average CRT looks like. This would be reason to send it to maintenance back then - it looks like breaking contacts or problems with the analog board.

A good CRT would show lines, but they'd be steady and not flicker (unless you self-inflict an interlaced display on a short phosphor screen). It might also show some color convergence issues, but that, again, is adjustable (or you'd send it to maintenance).

This looks like the kind of TV you wouldn't plug a VIC-20 to.

Uses @keyframes and text-shadow to try and mimic a CRT effect but makes the text unreadable (for me at least). The browser readability mode does work on the page though.

I think so too, and works on my old LCD monitor. If I focus on it, I can see the subtle changes, but other than that, it does not make it any less readable for me.