It’s supposed to be the case that if your rank preclude you from playing a ranked linked challenge, you get told this when you press the accept button.
This includes Guests, who will only be able to play ranked games with people who have a rank that is accessible with [?]. Roughly speaking, this means that Guests can only accept linked challenges from people < 2k , as I understand it.
Note that before we made the recent fix, you didn’t have a choice: “open” challenges were automatically shared on the Play page. Which is why we fixed that 