I've figured out something - this is regarding my comment on the multiple files to choose from - earlier. I just recently found out that my itch app will make a copy of the 'new' game version rather than overwrite the old one.
So that means - if you're using the itch app, and you seem to be weirdly low on space, check the game folders in case you're carrying older versions of the games, then delete the old ones, and you're back in business. At least that's what's going on for me.