So, this may very well be intentional, but not sure.
If you have a hero leveled up much higher than the costume, wear the lower leveled costume, then various sorts still sort by the higher base hero power rather than the costume power.
I can understand why they may do this, but I think it would be better to sort by the selected costume power.
Sorted by element:
Sorted by power:
In both cases the base hero is at 4/80, but I’m leveling the costume. Because I’m tired of changing him for a Titan vs my farming team.