I just got a notice telling me I've exceeded cloud storage limits for Battletech.
I didn't know I was using cloud saves. How do I turn that off?
Also when I checked everything is listed as being from Dec 6, 2022 for some reason.
If I let GoG delete it, will it wipe my local files as well? I don't care about the cloud storage, but I do care about losing my locally stored campaign.
Again, how do I check the settings?

I don't ever use Galaxy if I can avoid it. I see no value in launchers like that to ME and dislike Steam and Epic's. They just add extra overhead, allow for tracking and data mining and facilitate DRM to little tangible benefit for me. The only reason I use Epic or Steam's is that the games usually won't run without them. Well half the time in the case of Epic but Steam is pretty much all the time. Why I prefer GoG.

Gog Cloud Saves are only copies of the local saves, so you have to start Galaxy and BT, then delete the local saves you don`t want any more. There are alot of them, because BT saves after every bigger action (you can move the saves somewhere else, too. after that close BT and it syncs with Galaxy and the Cloud Saves will be deleted. Gog Cloud Saves are really good if you play on several comps and/or loose your drive. They are locally and in the cloud. If you dont want them anymore, just dont start Galaxy or disable them in Galaxy.

I don't start Galaxy if I can help it, but sometimes I click download and it launches Galaxy, or the installer launches it.
I want to delete the cloud saves, not the local copies, which I want to keep.

Then move them somewhere ... this will delete the cloudsaves when you do it while game and Galaxy are on. If you want to download games just use the offline backup installers, this wont use Galaxy

you can use a web browser to remove cloud saves

ref- https://support.gog.com/hc/en-us/articles/18730340487709-Review-your-Cloud-Saves-to-avoid-loss-of-files?product=gog