A Chipotle shareholder is suing the fast-casual chain over viral social media complaints about skimpy portion sizes.The proposed class-action lawsuit filed Monday claims Chipotle understated customer dissatisfaction regarding its “highly inconsistent” portion sizes in official disclosures. The lawsuit said that unhappiness wasn’t clear until the spring and summer of 2024, when customers’ true feelings spread on social media posts in a virtual pile-on.The lawsuit said a turning point was when mega-famous food influencer Keith Lee, who had previously collaborated with Chipotle, slammed the chain’s chicken portions in a May TikTok review. And, as the lawsuit cited, in June, a Wells Fargo analyst even ordered 75 burrito bowls to test portion sizes and found that the consistency of the portions varied widely.“We don’t comment on litigation and will vigorously defend our industry leading real food,” Laurie Schalow, Chipotle’s chief corporate affairs officer, said in a statement Wednesday.It’s the latest development in …