This is a common criticism of teacher unions in the USA [0]. They donate dues money to left-leaning political causes against the wishes of many of their members. In a union shop, dues-paying employees have no choice in the matter. It is compelled political speech.

I expect this will be a big issue in tech unions also.

[0] https://www.detroitnews.com/story/opinion/2019/10/16/opinion...