They already did. Event is over since yesterday
Jan. 22, 14:00:00 UTC - Cutoff for submission of FFA Mayhem Stars for the Free-for-All Mayhem category.
Looks like MA can't get their event right once again. The turn in should have still been around until Jan 22nd
You shouldn't let yourself be trolled.
Event is over since yesterday (probably meaning you can't get more stars), but people can still turn FFA points, and until the 22nd, just like the original rules stated.
That would be true, if the NPC to turn the stars into was still around. MA needs to add it back