Simply false. Historically, US labor unions were anti-immigration because of competition for their own members already in the country. Go look up Cesar Chavez's view on allowing more Mexicans (especially illegal aliens) in to compete against his United Farm Workers. Unions being for unlimited, uncontrolled entry from outside the US is a very recent phenomenon.
Incoherent and politically illiterate rants like yours aren't really appropriate.
I'm a left-voting Brit and I can see that. The endless accusations by the left US media, politicians, and activists of people being -ist has caused massive credibility damage. Not to mention, they have significantly devalued the real victims of genuine cases of -ism.
https://www.bloomberg.com/opinion/articles/2017-02-21/the-my... (not sure if you can see that but don’t have a better link)
What does this mean?
Anti-immigration dog whistling has been a fairly standard tactic for right wing politicians since the 90s, where John Howard referred to asylum seekers as illegals, railed against "queue jumpers", and called for immigrants to respect the "Australian way of life" [1]. Like Trump, Howard also constantly went on about how he represented "ordinary Australians", unlike the "elites" with their "vested interests".
[1] https://australiainstitute.org.au/wp-content/uploads/2020/12...
To me it seems like a category error, and I can't believe it's an accidental one. Some people do some things that we agree on are okay. Some go too far. That doesn't mean all do.
Slightly more broadly, I think there's a healthy discussion to be had on open borders, and whether immigration should be illegal at all, but constantly assuming someone means something they aren't saying is incredibly destructive to our ability to reason about topics.