Do you have Roms on there? That does it abit or external to steam games

Not 100% sure on steam deck but usually that “other” is the OS and system files

Install a program from the Discover store called Filelight. It will allow you to see which folders are taking up how much space.

If you don’t know what it is, ask here before deleting anything.

Nice, you’re using the pip-boy theme made by suchmeme and u/emmerson_biggons