Why does an electromagnet lose most of its magnetism when its current is turned off?

An electromagnet loses most of its magnetism when the current is turned off because it is constructed using "soft" magnetic materials, which are specifically designed to be easily magnetized and demagnetized.12

In these materials, the hysteresis loop—a curve representing the relationship between magnetic field strength and magnetic flux density—is very narrow. This narrow loop indicates that the material has a low [coercive force], meaning it requires very little energy to reverse or remove its magnetization.12

Unlike permanent magnets, which are made of "hard" magnetic materials with a wide, rectangular hysteresis loop that retains a high level of remanent magnetization even when the external field is removed, soft magnetic materials are engineered to lose their magnetic flux density almost entirely once the electric current is switched off. This property is essential for devices like transformers, motors, and other electromagnets where the ability to switch the magnetic field on and off or vary it is required.123