> This sends an encrypted blob of all your messages to Apple/Google, and WhatsApp holds the key

It is a plain text backup to Google Drive. There is no key Whatsapp holds. Google can read it all, and has revealed the chats to help the Govt in multiple high profile cases here in India.

You can extract it yourself, with the credentials of your Google account- https://github.com/YuriCosta/WhatsApp-GD-Extractor-Multithre...

> You’re referring to the optional backup that requires users to opt-in.

With telegram, if you enable secret chats, it is never backed up to the cloud. It is a guarantee, unlike Whatsapp where you do not know whether your contact has enabled cloud backups

Full disclosure: I begrudgingly use WhatsApp. I really don’t like it. You’re spreading misinformation, though.