https://www.bbdlc.com/blitz-bardgett-deutsch-on-behalf-of-regional-st-louis-entities-files-lawsuit-against-nfl-nfl-teams-and-team-owners-arising-out-of-relocation-of-rams-franchise/
Basically, the NFL failed to follow its own relocation guidelines and induced the City to spend millions of dollars on designing a new stadium and other damages mentioned in the lawsuit.
In layman's terms, the NFL did not negotiate with the City in good faith regarding the stadium and the relocation. In fact, going further, they outright lied about it from the beginning. They subpoenaed phone and email records to prove this and they also have them on public record lying about it. The depositions will make it even worse.
The NFL is f*cked and they know it. They've lost every single court battle on this lawsuit and are starting to get backed into a corner. You will be reading about a settlement sooner rather than later.