I’m not sure about delta one firms but almost all the options MM firms have been having record years in the COVID / meme stock era.

In broad strokes, the things that hurt market makers the most are long winded price trends and accumulation of inventory. So generally MMs can and often will eat large initial losses (depending on how many wings they happened to have owned at the time) when huge volatility spikes happen but when the raised volatility stays at that level for some amount of time (you’ll sometimes hear this referred as market “regimes”) and the MM was able to not blow out from the initial spike they’ll more than make up their losses from the good trading environment after the fact.

Market makers as a whole were suffering during the mid 2010s when volatility was low year to year, correlation with SPY was high, and all the indices basically just went straight up every month.