"Apple does the same thing with FileVault when you set up with your iCloud account where, again, previously your disk was just left unencrypted"
Nah, the FileVault key is stored in your iCloud Keychain when you choose to backup the key to iCloud. And the keychain is end-to-end encrypted. Only the user has access.
This user has been spreading this falsehood so heavily in this thread that it's almost suspicious.
When you store your FileVault key in iCloud, it is in escrow (ie accessible by Apple) on older but relevant versions of ios and macos. On newer versions, the situation is improved. However, the terminology on newer versions has changed from "icloud keychain", so frankly, I still think you were talking out of your ass.
Nah, the FileVault key is stored in your iCloud Keychain when you choose to backup the key to iCloud. And the keychain is end-to-end encrypted. Only the user has access.