The grandparent comment is correctly pointing out the sentence is an LLM tell.

"Membership is a question they ask a server" is a bogus sentence. "membership" is not a "question". It's syntactically valid semantic nonsense.

"Membership is dictated by a server" is one of several human sentences saying what that one is trying to.

Partly. Partly because using EUF-CMA pins the record to the CA which makes membership deniability non-trivial which I don't love. It's not dumb, it's what Signal uses AFAIK and in transit message deniability is different than the signer. But still..

Also that sentence structure is very claudelike.