Getting fainted with focus sash

I’m fighting Persephone in the dream realm. I have a delta Gardevoir with a focus sash but her mega spiritomb OHKOs through the focus sash. The only thing I could think of is that the tough claws ability is calculated twice rather than in one or there might just be a glitch with focus sash.
If you know why this is happening could you tell me?

Tough claws and mould breaker bypass it.

neither tough claws nor mold breaker bypass focus sash you were probably fainting because of getting hit by a multi hit move or not being full hp

I was getting hit by sucker punch. I researched a bit that was the only answer. Idk if it was a glitch but it answers it and it was full hp

Nevermind the source was lying lol