Looked up 2 of them, seems like they are settings and files, stored on Googles servers, but encrypted by the time it reaches Google.
Short of someone with a quantum computer, I doubt anyone will decrypt them, along with the billions of other user files out there. Suffice to say, don’t store/link anything sensitive if you’re worried.
Blocking might just break features, but be wary to see what’s broken based on what’s disabled and see if it can just be manually disabled in settings first.
No problem, I’m not exactly a fan of the cloud myself, but it’s being forced on us. It feels a bit like a fad, but I still store everything on secondary storage.