Hey fellow saltdogs! :D
I have a jellyfin server running on an old laptop. Now I have the jellyfin Android app and would want to play content with subtitles (anime weeabooo), Cast to my Chromecast. I was using VLC player as an external player on Android but casting with subtitles is not supported. Max Player had a lot of adds I have heard (?).
Anyone watching their content with subtitles via Chromecast? What player are you using?
i don’t know too much about jellyfin compatibility, but your issue is probably ASS/SSA format subtitles, which are a complex graphical overlay subtitle, rather than simple text so device support is less guaranteed.
You could try pre-burning the subtitles in before hand by re-encoding the video, or find content with SRT subtitles which have wider support.
ASS on android clients is mostly a solved issue these days so as the other commenter suggests, the google TV chromecast with a native jellyfin app would be a more reliable solution for you.