I use Jellyfin on Roku because my Samsung TV was too old for it.
It sucks on Roku.

I have not figured out the pattern for why some UHD videos don’t play remotely while others do, only that debugging it is fiendishly difficult since it all works fine locally.

If you ever resume a video, the subtitles are out of sync. And I haven’t found a way to adjust them.

Some videos with certain encodings play only on the PC app, but not Roku or Android.

For that matter Android is basically there to just easily download a copy, I don’t even bother trying to play with it.

At least Plex consistently plays things.