Minotaur Emperor drops old 'rewards'.
Killed Minotaur Emperor in ADOM 3.0.5 beta on Steam, received rewards from before Feature 1507 adjustments.
I just killed Minotaur Emperor (with spells) in ADOM 3.0.5 beta on Steam and received old rewards: Greataxe, 1 potion of strenght, 3 PoCC, 1 spellbook, corpse.
There was neither random additional artifact nor PoGA drop. :(
I like how the maze was made more accessible. It's still tedious, but at acceptable level.