So this surely means that in the medium term Google will siphon off all of the iCloud data. A dark pattern here, a new EULA popup for the user to accept there, and just like with copilot on windows the users will "allow" Apple to share all data with Google.

I wouldn't expect this to happen, as Apple's resistance against this would be too strong. The data of Google's paying [enterprise] customers stays private as well, so the safeguards are in place already.