CNBC reports that the National Labor Relations Board alleged, in a complaint filed Friday, that X violated labor law when it fired an employee who criticized the company. Elon Musk bought the company, then known as Twitter, in October and threatened to fire workers who didn’t return to in-person office work. After Yao Yue encouraged others in the company’s Slack to let the company fire them instead of quitting, she was fired for breaking an unspecified company policy.

CNBC writes that in the complaint, the NLRB accuses X of keeping workers at the company from exercising their legal labor rights. Yue alleges the company laid her off “in retaliation for her attempt to organize her co-workers not to resign, so they would have better legal footing” on which to challenge the company later.

In July, ex-employees of X filed a new lawsuit over the company’s alleged refusal to pay for arbitration that a judge had determined in January they were contractually obligated to use. The judge’s decision halted their class action lawsuit that alleged that X had not given the employees proper notice under both federal and California state laws. The company had begun laying off much of its workforce in November last year.