I think what happened was a the perfect storm: remote working made people be more at home and so more time spent online. Additionally, stimulus checks were juicy targets for advertisers that tried to sell people stuff to spend time.
Now, we are having inflation due to all those stimulus checks that forced central banks to hike interest rates. Moreover, energy prices and supply chains disruptions exacerbated the situation by driving more inflation and the cost of doing business. Advertisers understandably prefer spending less money.
Under these circumstances such a drop in unsurprising IMHO. Similar to the drop in Q1/Q2 2020.
EDIT: I wrongly used stimulus checks as an umbrella term. I really meant all the actions that pumped a lot of money into the economies.