It’s because of me, I installed Mint on an old laptop.

Very true. I have a couple items at work that don’t work when I pick “at startup” so I usually just go with the event log startup as the trigger nowadays.

Can you set the Jellyfin server service to start with Windows? Shouldn’t need a login then. If not, you can use a PowerShell script that starts the Jellyfin .exe and use a scheduled task to run it when event id 6005 is triggered. That’s the event id created when the event log starts.