I always found German unions pretty good.
I mean the union is correct in this case. Robots will replace jobs. A union’s job is to make sure there are jobs for people in the company they are already in.
Usually unions would speak the truth (“robots = jobs go away”) but pair this with some suggestions: eg trying to upskill the affected worker so that they can be moved to a different department).
While I was working in Germany I always felt better at a company with a strong union.