Deferred and Applying to Other Colleges

My friend was at first asking for me, but her post got deleted. So, I’m currently on a gap year and my school does not allow me to apply to any colleges during my deferred year. My question is: what is stopping me from applying to other colleges if they legally cannot share my private information between different colleges? Like, how would my college not find out if I don’t submit FAFSA? I know it is unethical and I’m just asking for peace of mind.