I seen many bosses level 60 with 1.500.000 power.

I think there are 3 level of bosses

Easy) Power= level * 10.000 - 100.000
Normal) Power = level *10.000 + 900.000
Hard) Power = level *10.000 + 7.690.000

Until 59 boss kills player only get easy bosses.
From 60-99 player get easy or normal bosses.
From 100- player only get easy and hard bosses.

I think before fix players just got easy and hard boses from level 60-.
Players WHO got 100+ kills before fix might not have seen then 1.5M level 60 boss.