But the very fact that you go to "chatgpt.com" and write to them; "Dear Diary, today I thought.."; there is no reason they would not receive and process your data, unless explicitly promising not to (which also requires us to trust them).

The fundamental rule in this case is that if we offload our data to a cloud provider we can assume they read it, if they can, unless they promised very clearly they will not.

Every single internet connect piece of software there is probably collects telemetry at this point. Why would this be any different? You know google logs your search data as well right? Not just the companies scan it but law enforcement too.