Pokémon Go players report a new new anti-cheat feature in the app - which hides rare monsters from naughty accounts.
In fact, if developer Niantic has flagged an account as cheating, it will only display common creatures like Pidgeys.
Evidence of this was dug up by PokémonGoHub, which noted that it was, so far, mostly being used to target accounts set up for use by third-party tracker apps.
These apps let users see which Pokémon are nearby using bot accounts that spoof their location and then log-in to Niantic's servers.
Niantic has continually fought back against tracker apps since last summer, when it complained the services were creating an unsustainable load on its servers.
But the developer has also spoken out against trackers from a more moral standpoint - Niantic boss John Hanke has previously commented he did not like their added functionality, as it was not the way Pokémon Go was intended to be played.
"People are only hurting themselves because it takes some fun out of the game," Hanke said during a San Diego Comic-Con panel last year.
But tracker apps remain popular with the Pokémon Go audience - who argue the third-party solutions actually encourage play.
Regardless, this latest feature will need continual updating. Tracker creators have already begun creating new accounts to get around those flagged as cheating. And so the Pokémon Go tracker war continues.