I'm going off the top of my head here, but you can watch Netflix in 1080p (and 4K I believe, I only have a 1440p monitor) on Edge, to see up to 1080 in chrome or FF you need an extension with 4K not being possible.

I don't know if it is a tech-issue or legal, but since it can be fixed with an extension, I guess it's tech?

So is Safari, there's only really two engines now, Chrome (Edge, Safari, Opera, Brave, et al) and Firefox (Tor).