The economy gets worse. Ad spending goes down. Google's search revenue decreases. Mozilla's search deal with Google is less profitable.

During the pandemic, fewer people have been searching for (and more importantly, purchasing) niceties. They're buying things like toilet paper. That's going to directly affect ad revenue.

I wouldn't understand it either if I wasn't exposed to it. It's not something I can disclose but the general concepts at play are human reactions to risk. There's a short term boost in impressions across the internet as individuals are locked down. They order more delivery, they order more from the brands they trust, but they don't spend more during an economic downturn. We're for the most part less inclined towards risk during uncertainty. The forecasts for fully recovering to mid 2019 vary by industry but some of the largest ad buyers were the most affected. They don't care about a short term increase in ad views when no one is gonna buy their service. The largest retailers also run their own ad services so the amount of pie left after everyone has their cut isn't something that keeps many employed.