One would have to work hard to prove they were NOT biased in the first place, or at least since 2011 when they sold out to the movie industry.
FYI, the other big name in movie reviews, IMDb, has been owned by Amazon since 1998 (color me surprised, I didn't know it had been this long until I checked on Wikipedia), and they also had their own streaming service, IMDb TV, now called Amazon Freevee.
When IMDB was sold, it was seen as if wikipedia was sold to a private company. Amazon promised to leave IMDB mostly alone, and to provide data feeds / db backups for free. They are still available although new features of IMDb have not been migrated to the original datasets.