@greghendrix I wouldn't go as far as saying no matter what we do, but yes: privacy online is hard to get right. 😓 You are out of luck if the service provider has the keys to encrypt and decrypt your data.
To keep something secret from third parties, you and the person you're communicating with must be the keys' sole owners. That's end-to-end encryption. Element, Session, and Signal are three alternatives for sending messages end-to-end encrypted.