There is no harm, but it is not recommended to eat things heated by microwaves often, because many things are counterproductive. Although science has not yet identified them, they still need to be verified.

Microwave is physical heating;

Microwave particles in the furnace cavity will make active molecules such as water molecules and fat molecules in the object oscillate and rub at high speed, so that the object itself generates heat and heats up.

The injury mentioned above is that the heating time is too long, and the water molecules will oscillate and rub at high speed under microwave heating, which is bound to lose water instead of destroying nutrition. Microwave heating can protect nutrients from loss, and steamed bread can be heated for 30 seconds.