Palworld. Helldivers 2 still had the backing of Sony and was a sequel to a game that had its own little cult following.
On the other hand, you had a small indie team of what started out as only 10 developers turned into a phenomenon that turned into 20 million players within a matter of just a few weeks.
Helldivers 2 may have the better longevity, but Palworld was the bigger surprise.