It’s really important for people to understand that E2EE cannot protect the message portions that aren’t between the ends themselves. The best encryption in the world can’t help you if the person you’re talking to is an undercover cop, because that “end” can do with the plaintext whatever they want, including record/store/forward the plaintext of any messages they then encrypt and send, or any messages they receive and then decrypt.

That’s not a flaw of the E2EE protocol itself, but is a limit to the scope of protection that E2EE provides.