Likely mentors as the other comment said.

A band-aid to the problem would be to set the might to at least 4k and to only allow the element you are looking for.

If you leave the might low, mentors will see that as a possibility that a mentee is in there and flood your room. The higher might you specify, the more obvious it is that you are farming and it communicates to them from the lobby search that there probably isn’t a mentee in there and leave your room alone. Some mentors will come in to check anyways, so it isn’t an ideal solution.

Mentors also like to use the ‘Join Co-op’ function so they can screen multiple HDT lobbies and quickly swoop in to check for an eligible mentee. By restricting your room to a particular element, you can at least curb a portion of mentors using the ‘Join Co-op’ function.

Finally you can change your IGN to something that lets players see from the lobby that you are farming. I see players generally going with “FarmHDT,” “FarmOrbs,” Farming,” or my personal favorite: “NotMentor.” This, however, will probably ineffective at dissuading Asian mentors from joining your room anyways.

If you are thinking, “Wow, fuck those guys!” Then you are right! Fuck those guys, indeed!