Id first compare the positions taken in previous days VaR vs Today, then check the new prices that have gone in the VaR window. If underlying has spiked, it will affect the VaR too. There could also be a possibility that a trader has taken off some of his position and now he is more exposed because less offsetting. This is for historical VAR but Im guessing the same applies for othersensitivities.

AI led rout. They rallied too much with capex in AI not matching expected returns. I hear some people say AI rally is like the dotcom bubble