Personally, I just can't stand playing Larian Studio games. It's like playing with a vindictive DM. It was especially noticable in Divinity: OS2. I played as the skeleton guy who was permanently disguised. I'll encounter a random group of enemies.....and somehow, they just know to use heal on my undead guy to hurt him? He's disguised, what the fuck? Every enemy whether man, animal, or demon knew every weakness, knew which players had the lowest weaknesses, and would exploit the absolute fuck out of them. Exactly like a vindictive DM would.
Yeah I agree that's rough, and probably an unexpected interaction. That being said, other than that, I've played pretty much all Larian Games (even Divinity 2: The Dragon Knight Saga) and I've never felt like the game is working against me, but I have felt like the game is of punishing difficulty in some unexpected ways. When you make a game with so many permutations, there are bound to be issues with some of the edge cases. Not defending them, I'm happy you shared a legitimate complaint, unlike the OP review which isn't a legitimate complaint, but is clearly just salt.
Your particular scenario does seem frustrating, I agree.
For the vindictive DM? Oddly enough, I like that! Lots of subversion to keep it interesting. At least for me who suffers from "pick one strategy in the beginning and run it to the end game".