The stat block for the Huge Gray Ooze indicates that on a hit its pseudopod deals:
6d6 acid damage plus 2d6 acid damage, or 12d6 acid damage while the ooze is enlarged.
Looking at the smaller gray ooze’s stat block, it seems that the additional 2d6 damage is possibly an error. Furthermore, the source material for the creature seems to indicate that the additional 2d6 is not intended either.
How much damage is the Huge Gray Ooze supposed to deal when it hits with their pseudopod? Is it effectively 8d6 acid or 6d6? What about when it uses the Enlarge feature on itself, which doubles the damage dice for the pseudopod?