The National Labor Relations Board (NLRB) is accusing Grindr of using a return-to-office (RTO) mandate as an attempt to block employee efforts to form a union.

About 80 of the 120 workers who were trying to unionize left due to the RTO mandate, Bloomberg reported on Monday. Grindr was said to have 178 employees when it announced the mandate, meaning it lost about 45 percent of employees overall.

The NLRB’s general counsel office followed up on Friday with a complaint against Grindr, saying that the RTO mandate was issued illegally in retaliation for workers unionizing, Bloomberg reported Monday. The NLRB is also accusing Grindr of breaking the law by not recognizing or negotiating with the union.