Starbucks’ Howard Schultz, who was interim CEO at the time, broke federal labor law in 2022 by telling a California barista who raised concerns about unionization that “if you’re not happy at Starbucks, you can go work for another company.”
You can file complaints with NLRB or civil suits about lots of things, but the details matter if you want to go anywhere with them. For the most part, unionizing and union related activities are protected actions, within reason as defined by law. If your action is union related, and they fire you, and you have some reason of evidence that it happened in that way, then you might want to look into following up on it.
As always, expect your bosses and HR to lie about what happened. It's really good if you have video evidence, or at least multiple witnesses, and certainly take notes right after having any such incident.
My car up and died so I had to take a loan out of my 401k to replace it, I can't quit till I can pay off the remaining balance in a lump sum (or till another year passes)