They added back the mechanic that the Coven bosses need to be kept apart or they become immune. That was not present for the first half of BfA.
Also, mythic Eonar requires 4 players to go up to the ship and enough strong dps running around to kill all the trash.
There’s always transmog groups in the group finder. If somebody is looking for gold, there’s way easier ways to get it than soloing mythic Antorus.