Even if you noticed 2 seconds after using the thing, you still shouldn't scum the save to get those stats back.
You should accept the narrative consequence of her being weaker as the result of the narratively bad choice of her using the thing.
If you don't have a narrative justification for not letting her use it, which you obviously didn't since you used it, you should take her reduced stats not as a mechanical result, but a narrative one.
And frankly, it's an objectively good one. You weren't punished, you just moved the story forward in the direction that matched events.
In fact, I have to consider the possibility that they intentionally didn't provide an excessively obvious visual specifically for the purpose of stopping players from noticing for a while, to the end of preventing players from devauleing the story and the game as a whole by save scumming this.
