Excessive RAM consumption

[TheDreadPirate]

Most of the memory jellyfin uses is cache.  Memory used for caching and reserved memory for applications and application data behave significantly differently.  If another app needs more memory, the cached memory will be immediately released to the other application.  Most  dashboards, like the screenshot you provided, do not distinguish between reserved memory and cache.

I'm running into this same situation where Jellyfin holds onto cache indefinitely; bare metal this is of little concern but I'm running it in proxmox and want that memory freed up for other VMs.

Assuming it's expected for jellyfin to hold data in cache/buffer indefinitely, how can I change this behavior? If it's not expected, what could be the issue? I'm running Jellyfin v10.8.13.0 pulled from Ubuntu's repos (i.e. not a docker image). Github says the env variables to help with memory consumption should be within this version so I don't know what I can really do here.

You could just give the VM less memory.  It just won't cache as much.  Caching does not prevent Jellyfin proper from using the memory it needs to use since cache is immediately released when other apps needs to reserve memory.