Steam likes to keep in memory what mods you subscribe to in Workshop. So, you could of uninstalled a game and then came back to it some time down the road. Then you install it and Steam will download the mod from Workshop. This is why it's 'kind of' important people should first 'unsubscribe' any Workshop content from a game prior to uninstalling the game. Then (hopefully) steam clears it from your profile for that game. I've seen this happen first hand. Not sure the Steam Devs intended it that way but, it's happened that way for me before.

At this point, I'd go unsubscribe any mods and do an uninstall. Then do a restart and do a clean install for the game. You could set aside your game save and drop it back in after the clean install. I also wouldn't use that 'Cloud Sync' option in the game properties... maybe disable that prior to uninstalling. Or, you can be like many others taking a chance and relying on steam to accurately back up your game saves to their servers. It's just not my preference cuz of how many times I've seen saves get corrupted from it.

Prob of some other game