Crystal cave bugged?

Smurff3d

So i was playing mew vmax vs zaccian v and i had a double turbo energy attached and a choice belt it should be hitting for 220 against a zaccian v by copying genesect v attack. There was no other pokemon in play with a stat lowering affect. The only thing i did notice different from the turn i attacked vs the previous was crystal cave was in play. Crystal cave lets you heal your metal pokemon once per turn which that still worked. However i was dealing 30 less damage so my guess is crystal cave is bugged.