This is intentional. Opinions?

It's a powerful and rare potion, IMO the earlier behaviour was good.

I'm happy with the new behavior, makes much more sense. The old effect was too powerful IMO.

I also feel it's a good behavior, PoGA are perhaps rare but there are 2 guaranteed stacks in the game that total 9 potions.
This means 9 increases of all potential attributes, which is a huge amount. 16 if you take greater black unicorn quest.
I think only poolsipping and blessed potions of specific attributes should increase potentials above base attribute value and only by one.
Everything else, herbs, corpses or poga should only increase base stats and potential by one, so that if you've reached your potential you won't be able to train that extra point.