That's why I said "behind an experimental flag". Search for "private network" in chrome://flags.
Oh I see what you mean. The default blocking behavior in Chrome 94 only applies to public non-secure contexts. We’re talking about a stricter form applied to secure contexts here.
https://wicg.github.io/private-network-access/
https://developer.chrome.com/blog/private-network-access-upd...
Also ws/wss has no SOP/CORS which could be a problem, but that has nothing do with the domain blocking here.