The principal issue with Bohemian Rhapsody was that, good central performance aside, it was just rubbish. It's also been castigated for its approach to Freddie's sexuality, and for factual inaccuracy (Queen never broke up during Freddie's lifetime; Freddie wasn't diagnosed with HIV until well after Live Aid, etc.)
Of course, factual inaccuracy is a criticism to be deployed with caution. Of the eight films nominated for Best Picture, five are biopics or otherwise based on a true story (The Favourite, Vice, BlackKklansman, Green Book and Bohemian Rhapsody), and none of them is accurate. All of them probably fall victim to the common trope of "villainising" relatively innocent individuals for dramatic effect in order to provide the film with an antagonist, although at least in The Favourite's case everyone depicted has been dead for a few hundred years.
It is after all possible to be entirely inaccurate in one's portrayal of real events and yet still be quite a good film (hi there, Braveheart!) Bohemian Rhapsody was not.