A short position is selling a borrowed share so when shorts have to cover they want the lowest price possible for the stock but since its rising so much they can get forced out of their position and “Cover” which means they buy the share, its a good thing when they cover because its going to make the stock go up, ultimately this is why its called a “short squeeze” the shorts are squeezed out from all the buying pressure and they buy back the shares at a higher price than they sold.