The plaintiffs, Jason Zajonc, Danyael Williams, and Pranko Lozano, claim that EA's patented Dynamic Difficulty Adjustment technology has been used to manipulate people into buying more loot boxes in games like FIFA.
You're probably wondering what Dynamic Difficult Adjustment technology is. In short, it's pay-to-win under another name. While gamers have long been intolerant of "pay-to-win" mechanics in EA's more traditional gaming offerings, in sports titles, it's fairly common for players to "unlock" better or worse versions of certain players via loot boxes, which directly impacts their ability to win games. This Dynamic Difficult Adjustment technology can apparently be used to misrepresent the skills or levels of the players someone uses, making the game harder and thus encouraging them to buy a few loot boxes.
"This is a self-perpetuating cycle that benefits EA to the detriment of EA Sports gamers, since Difficulty Adjusting Mechanisms make gamers believe their teams are less skilled than they actually are, leading them to purchase additional Player Packs in hopes of receiving better players and being more competitive,"
They're accusing EA of violating California consumer protection laws, as well as false advertising and unjust enrichment. They're suing for restitution and corrective actions.
For what it's worth, while EA has had a patent on the Dynamic Difficult Adjustment technology for a few years now, EA also claims they don't actually deploy it in many of their games. This wouldn't be unprecedented -- it's not uncommon for companies to file patents for things they don't ultimately use -- but it would be fairly out of character for EA not to try every sleazy trick in the book to get people to spend money.
It'll probably be a while before we hear the results of this, if any.