- Nothing is wrong, you're just not strong enough to maintain your back position.
- I recommend against intentionally doing this. Until you're an advanced lifter this is just a cop out against getting stronger and maintaining better positions.
- Good. Activation isn't a yes/no thing. You can always "activate" more to stay tighter. Keep practicing this and you'll get stronger.
Most people have weaknesses from the beginning that make them stronger from non-ideal positions. If you keep practicing with perfect form your weakness tend to correct themselves and you'll get better at pulling with good form. Practice with shit form and you'll keep exacerbating weaknesses and just get better at pulling with shit form (and as a result you'll hit a wall with progress sooner).