Secure E2E encryption makes companies unable to decrypt encrypted data upon request.

Therefore, a law forcing them to decrypt encrypted data upon request necessarily makes it illegal to implement secure E2E encryption. QED.

(If the law only allowed them to share with the government data that was already decryptable by third parties, that would be a different matter. That's what happened to Tutanota in Germany: the tribunal ruled that they had to allow the police to access messages sent as cleartext, but they could not be required to put a backdoor in their E2E clients.)

"E2E encryption ban" != "encryption ban"

Semantics. E2E is necessary against a wide array of threat models and is a fundamental part of what can be considered 'pretty good privacy' by 2021 standards (pun intended).

If a government, possessing a working set of quantum computers, chose to ban post-quantum crypto algos only, by the same semantics it could be argued that it would not be a general "encryption ban" either.

I think it's clear we're talking about effective, secure encryption, and that means E2E. Faulty implementations are technically an exception, but I don't think you can argue with that in good faith.