From my European pont of view, I think the definitions of left and right have shifted a lot.
Sure, in Europe left and right may be more closely matched in academia, but most "right"-leaning Europeans would not be anywhere near the "right" in US-terms, so your argument is comparing very different things
I have seen so many claims like this one, yet never any evidence of this sort of thing actually happening. I tend to believe this is a combination of confirmation bias and "side-channel" information like googling related things, or pattern recognition on the ad server's ML side (e.g. if you visit the amazon toilet paper section once a month, and after almost a month you start talking about toilet paper, getting served toilet paper ads might seem suspicious, but it really isn't).
Is there any actual information about this somewhere? With the insane breach of privacy policies and laws this would be, I would think many researchers would have looked into this by now.