Not A Bug Some abilities can cause moves to do more damage than usual

[JustABitToxic]

What type of bug are you reporting? Random Battles

What is the bug?
When I was battling in random battles, the rival had a Sceptile with gigadrain, doing like 25% of damage. My clefairy used moonblast, Sceptile's Spatk dropped, but the gigadrain became stronger, like instead of a drop was a boost, here I have thw link, the thing starts at turnn 18
https://replay.pokemonshowdown.com/gen9randombattle-2175884119

Are you able to replicate it? If so, how?
I dont think so

 

[Chains of Markov]

The Clefable had the ability Unaware, thus the stat drop being ignored. Sceptile had the ability Overgrow, which makes Grass moves stronger when it is at low health.