It’s always been this way IIRC.
That’s not quite it. Think of it as being three stages:
- 1: You’re not Entangled yet. Your Atk is whatever it is right now.
- 2: You’re Entangled now. Your Atk is 0. No matter how much you gain, it’s still 0.
- 3: Entangle ends. Your Atk goes back to whatever it was during Stage 1.
It doesn’t matter if you gained Atk during Stage 2, because the moment you gained it, it instantly changed to +0.