When a Shadowbringer or Endwalker S rank dies, there's a ~10% chance that they trigger an event where 4 B rank minions appear on the map. After killing them, Forgiven Rebellion (Shadowbringer) or Ker (Endwalker) spawns, giving even more rewards (nuts/tomes/materias) to the players.

About those minions: they spawn with a 5min buff, that disappear when you pull them. If they are not pulled and this buff runs out, they disappear/flee. As long as they have a target, they will not flee.

Some players have been abusing this mechanic, and while having top aggro on those B rank minions, run away from the spawn point of said minion. Once the minion reaches a far enough distances, they return to their original point, but they don't have the buff anymore, and thus they disappear.

This falls under the Square Enix prohibited activities listed in ◆Obstruction of play・Obstructing Gameplay Using Combat, as they use enmity based interactions to impact the gameplay of hundred of other players; yet some people still do it.

Why does this 5min buff feature exist? Why don't the minion get back their buff when they return to their spawn point? What does it take to get any GM action on those players?