The moment you visit a website or app with ad space, it asks an ad tech company to determine which ads to display for you. This involves sending information about you and the content you're viewing to the ad tech company. This ad tech company packages all the information they can gather about you into a "bid request" and broadcasts it to of potential advertisers.
These class actions could have a significant effect on how companies engage in digital advertising in the future, and being willfully blind to their progress only exposes companies to increased litigation exposure.