I am actually more concerned about the shared farm. People are using low level characters (2-5) to tag the transformed mobs to get additional bags. The lvl80 will then kill them. This allows up to 5 people to farm the ToT bags simultaneously in the dungeon. Potentially more in open world (such as Rata Sum), depending on the damage per hit.
Doing this allows for a single vial to yield (5×9) 45 ToT bags. If you don’t deem this exploit then I really don’t know what would be called an exploit any more.