Jobbie123, what your company practises is common, nothing to worry about. They allow you to take advance leave is good. As some companies do not even allow you to take leave before you have earned it.

If you resign and you have taken advance leaves, of course they will deduct from your salary. Else, you think finance people stupid meh.

Compulsory leave is also common, some manufacturing companies shutdown 1-2 weeks per year, and everyone has to take leaves during the same period.