Episodes of The First Podcast are almost always recorded live on the Discord server. Anyone can tune in if the episode is a regular one and not a bonus one, but obviously only the hosts and the guest(s) are unmuted outside of the live question segment.
For one reason or another, someone in the audience will inevitably ask why they are muted and can't talk during the recording. The current record for someone doing this is about thirty seconds into the episode.
Some people who do this are probably younger folks who have showed up because of the guest in question, and maybe don't understand exactly what is happening, so they assume it is a normal voice call (albeit with an abnormally large amount of callers) and get confused.
Others do so as a joke to elicit a response from the hosts.