Here's the claim from the article:

The complaint alleges that the WFA “organized an advertiser boycott of Twitter through GARM, with the goal of coercing Twitter to comply with the GARM Brand Safety Standards to the satisfaction of GARM.” And it claims that these efforts succeeded in harming Twitter/X, with “at least” 18 GARM-affiliated advertisers stopping their purchase of ads on Twitter between November and December 2022, and other advertisers “substantially” reducing their spending.