Gold futures market has run out of gold to deliver as metals refiners shut down and air lines grind to a halt because of Covid19. The April gold contract is currently short of 55% of the gold needed to deliver (needs 19.6 Moz, only has 8.7 Moz to deliver). This is the reason for the rocket.
Of course one way to solve the problem is to buy back what you sold. But who is going to do that?