I’ve found that as well with some files. At first I thought the issue was with the jellyfin instance had not enough capabilities, but after trying the same file with its subtitles, it worked on any other client: flatpak, web, and regular android. So for me it is the chromecast/androidtv device, so I am now looking what to replace it with

https://sonoff.tech/product/diy-smart-switches/zbmini/

I have installed LEDLUX smart wall socket (around 25€), MOES light switches (around 30€ for a 2-gang switch), both of which are quite easy to install as it replaces what you already have. I have used Sonoff zigbee relays (around 50€ for a pack of 4) as well as Avatto mini zigbee smart switch modules (around 20€, single and 4-gang modules), but it may require some modifications on your current installation

Or go with a zero, plug and play socket, like the Nous A1Z smart socket, around 15€ each. Just plug it onto your wall socket.

So you "self"host elsewhere?