A glass screen protector cannot be compared with a normal screen protector. Where a normal screen protector consists of a plastic adhesive plate, a glass screen protector is a hardened piece of glass. As a result, the forces exerted on your mobile, for example by a fall, are absorbed by the screen protector. This will not crack the screen of your mobile, but the glass screen protector.
Then you can simply pull the glass screen protector off your screen again and then put a new one on it. The advantage of this is that you don't have to put a new screen on your phone if you drop it, just a new glass screen protector protector is enough. Simple, fast and cheap.