Sounds like a future Lower Decks episode to me.

The gang goes infiltrate some fancy pants Starfleet symposium -posing as captains because reasons- in order to find the infiltrator. But it turns out they're all infiltrators.

Section 31 actually knows about all the infiltrators, but at least in early stages of their infiltration when they're trying not to arouse suspicion they end up doing a better job than the human admirals would have anyway, so they're allowed to do their thing.

Must be interesting for the Changeling pretending to be a member of Species 8472 pretending to be a Romulan pretending to be a Vulcan.