Every event has one short link for the people you would rather post to than invite by name. Share, on the event page, opens it with a QR code and a poster.
The link exists once someone is invited. Pasted into a message it opens as a card with your photo, the title, the day and the place. Share hands it to your phone's share sheet; where the browser has none, most computers included, the button is Copy link. Scan to open is a QR code for the same link, and Download saves the poster: the title, the date and time, the place, your photo and the QR code, ready to print.
Allow public replies decides who can answer on it. Off, which is how every event starts, anyone can open the invite, but only people already on your list can answer: they type the mobile or email you have for them, and the answer goes on their own row. Anyone else is told you don't have them on the list.
On, anyone with the link can answer with their first name and a mobile or email. They are added to the event and to your People. An event takes up to 30 invites free and up to 150 paid; past that, a new person is told the event is full.
Turning public replies off later doesn't break the link. It stops new people joining; everyone already on the list, including people who joined through the link, can still answer.
The shared link never addresses anyone by name, so it is safe to post anywhere.