The Communications Workers of America (CWA) has filed an unfair labor practice charge against eBay-owned TCGplayer on behalf of workers at the trading card marketplace. The organization says TCGplayer supervisors and managers, including founder and CEO Chedy Hampson, illegally surveilled union activity in recent weeks.

Workers at TCGplayer are trying to unionze and this week, a supermajority filed for a union representation election. If they’re successful, they’ll form TCG Union/CWA, which will be the first union within eBay.

The CWA claims that TCGplayer higher-ups have walked the floors of the company’s authentication center in Syracuse, New York. It says the supervisors and managers were taking note of employees who wore clothing or badges that identified them as supporters of the union drive. “This conduct constitutes unlawful surveillance of union activity and further created an impression of surveillance designed to interfere with, restrain and coerce employees in the exercise of their rights guaranteed by Section 7 of the National Relations Labor Act,” the CWA said in a statement.

The workers renewed their attempts to form a union after eBay bought TCGplayer late last year in a deal worth up to $295 million. They previously tried to organize in 2020, but withdrew their union election petition a few days before the vote. The CWA says that TCGplayer thwarted those efforts by bringing in a union-busting firm and running “an intense anti-union campaign where workers were regularly ordered to attend captive audience meetings and disparaged by management in company communications.”

Engadget has contacted TCGplayer and eBay for comment.