4 characters were nerfed. No extra resources are gained from selling them. Getting extra ISO and HP for selling a changed character has happened for every changed character.
Surely this is bug.
This was addressed in this post which I’ve quoted below for you.
Might as well include Daredevil too, since he did not have increased byuback too.
( Even though all his abilities recieved a nerf. max dmg, max stun turns, and max AP steal - all lower on new version )