Group is on the free plan. Created event and checked "send invite to group".
A while later a message is posted that says "Accepted: [xxx] Event: xxxxx" from one of the members.
Since the group does not have RSVPs, I'm asking myself - "Where did that come from?" or more accurately "How did that happen?"
I imagine that the member's calendar sent a response to the group when they saved the event from their email or some such.
In my Gmail, it parses the invite email and offers "Add to calendar »" which creates an event in my calendar. Doing that and even clicking "Yes I'm going" did not generate a reply back to the group (which makes sense because it sees me as the organizer of the event, not the group).
Just posting as a "behavior to be aware of" as I'm not sure it's a bug. But I doubt the member expected a message to be posted to the group that she was coming the meeting.