I believe the explanation for this is that left-wing news sources have generally received higher fact check scores and Google now ranks search results by authoritative sources. As a side note, they seem to do this much more aggressively on YouTube and these days almost any search on YouTube will return videos from various mainstream media channels.
Being charitable, I do think right-wing news outlets have a problem with bias and misinformation and I can understand to some extent why sites like Fox News and Breitbart do not rank well in Google search, but on the other side, I also see huge amounts of bias and misinformation coming from left-wing outlets like CNN and The Guardian which rank comparatively very well.
There is a lot of soft censorship happening on the web today which most average internet users aren't aware of. The majority of search results and recommendations on tech platforms are far from neutral. For example, good luck finding anything negative about COVID vaccines on Google. Popular subreddits like CovidVaccinated are seemingly removed from Google search results completely probably because users on that subreddit tend to discuss the side effects they experienced after getting vaccinated or how they caught COVID despite being fully vaccinated, which obviously isn't good if you care about protecting the narrative that vaccines are 100% safe and effective. Again being charitable, you could argue that it's in the publics best interest not promote communities like CovidVaccinated, but right or wrong it should be understood that the content you are consuming is biased and deliberately altered to promote certain political narratives.
These days I do my best to avoid Reddit, Google and YouTube entirely when researching anything vaguely political because what I know what I will see is a biased representation of reality. The problem is most people don't understand the extent to which sites like Google and YouTube are biased and therefore believe what they're seeing is representative. And so should they decide to research COVID vaccines using Google there is only one conclusion it would be possible to come to.