It’s kind of the opposite of this though, it’s not censorship. It’s not that you aren’t allowed to visit other sites, it’s that sites can choose to let you in or not.
The scary part is we don’t know what makes that decision, and from Google’s proposal is that it could just be anything they decide. So it’s not censorship, but it is saying “You aren’t playing by our rules (like by using an ad blocker, or you visited too many whistleblower forums, or we just plain decided we don’t like you) so you don’t get to use gmail/your bank/whoever decides to implement this”