You can’t, it’s no longer end-to-end encrypted. The way proponents say it works is by “client-side scanning”, i.e. an app scans messages before they are encrypted. Of course, that just redefines one of the ends of “end-to-end encryption” - instead of you, the scanner is now one of the ends.

So previously, one end of a message trajectory’s is where you type it, it then gets encrypted and sent to the receiving party (the other end), who can decrypt and read it. After Chat Control, you type it, it then goes to the scanner, which scans it and potentially notifies a third party of the content, and then afterwards it gets encrypted and sent to the receiver, who can then decrypt it.

Yes, calling that end-to-end encryption is indeed a perversion of the term.

By forcing the providers to open their end-to-end encryption.

By scanning directly on your device after you’ve decrypted the message.

…

It’s not, unless you know the keys.

Keys are created by the software/app made by the service provider, like WhatsApp / Meta or Google. How is the key created, and is a copy sent back to WhatsApp? “Securely” and “No” they claim, and you just have to trust them.
That can change if WhatsApp need to comply with new laws.

Signal is a bit different because of the app is fully open source, so the code can be audited to verify the integrity of the encryption. They would still need to comply with laws or exit that market, but whatever they do would be 100% transparent.