Every year, Satisfactory releases a holiday themed event that lasts for a couple of weeks that applies to singleplayer games, multiplayer sessions, and dedicated servers. Thankfully, if you're not feeling it this year, you can use the following steps to disable them.
1. Open the File Manager
2. Navigate to /steamcmd/Satisfactory/FactoryGame/Saved/Config/LinuxServer/
3. Right click GameUserSettings.ini
and click Edit
4. Find the line that says mIntValues=()
5. Replace this with mIntValues=(("FG.DisableSeasonalEvents", 1)
6. Save the file and Restart the server