Sub panel and neutral and ground bus bar
You are probably in violation of National Electric Code, article 250.32(B)(1) states that the grounded conductor(neutral), shall not be connected to the equipment grounding conductor(ground).

The general rule of thumb is the only point the ground and neutral get bonded together is at the first point of disconnect for any incoming system, be it utility, generator, or some other source. There are a few exceptions for specific situations but none of which I feel apply.

Easiest course of actions is to kill panel, un-bond bars, drive screw through one bar into chassis and make that ground bar, use the other isolated bar for neutral. With no other knowledge of your installation I would advise you be careful of the loose neutrals while making the swap, if any are somehow being used by circuits from the other panel(it happens) they could shock you.