Jellyfin has Swiftfin, I’ve been using it for a few years now.
There are some small bugs that you can work around. The rework to the new version has been in progress for about two years but it works just fine right now.
Small bugs? May be. But there’s a lot of lack of functionality and stability. I’d recommend InFuse if anyone is hitting those problems. If it has been running fine for you then there’s no need to switch.
The problem is related to source codec. Depending on that you’ll have difference experience. So that’s why the experience varies because there’s vast differences in source formats.
A good client not only handles well on some sources, but many if not all.
There are some small bugs that you can work around. The rework to the new version has been in progress for about two years but it works just fine right now.