There is a bug regarding Ultra beasts. Ultra beasts or at least some so far I've seen obtained by breeding 2 dittos together to get a random Pokemon. Looked at the 7.0.6 changelog and it doesn't look like it's been fixed. As you know Ultra Beasts are in the undiscovered Egg group so they should be unobtainable from breeding 2 ditto's together to get a random egg.
Images showing player on the server having hatched 2 UBs, both level 1, he does not have access to commands like pokegive and he is a well known player on the server so I doubt hacking would be a possibility.