That’s a good point. One of the two biggest weak points of a so-called e2e provider/platform is, the e2e provider itself.

The only true e2e is e.g. Alice does gpg -ea on an offline computer, copy-pastes ascii and sends it to Bob via an online computer, who copy-pastes this ascii to his offline computer and does gpg -d there. Their seckeys are airgapped from the communication channel. Sharing your sec with a provider is especially ridiculous (e.g. Proton). At least that’s what I think.