As a strong supporter of unions, that's the end of my donations. I've probably donated fewer than a dozen times, but definitely more than five or six. I felt reasonably good about it and went on with my day, no hesitation about supporting them. That's done. Fwiw, unions often have support pages where you can donate or buy merch to support. One of my favorite tshirts advocates for a union that was trying to form at a…
Curious why you support unions in general? It’s kind of like saying “I support governments” or “I support companies”.
There are certainly examples of both social structures being wielded to bad ends, but I don’t see anything unreasonable about supporting them in general. Same presumably would go for unions.