Upon leveling from 8 -> 9, the maximum health of everyone in my party dropped, almost by 60 points in some cases:
Note that Karlach has 146 max hit points, although the odd thing is that the numbers don't match up in the tooltip.
After leveling up, Karlach has 80 maximum hit points. It lines up with the tooltip now, but where did those hit points go and where did they come from?