If the author is biased, does this interfere with the way you read and understand the text?
This specific idea always speaks to me. When it comes to persuasive work or research, I struggle to believe the author if they don't consistently counter their arguments. To me, it's a mild form of censorship. Failing to address the other side of an argument has got to be one of the quickest ways to ruin a text.
When and where was the piece originally published? Research the original publication. Does that publication have a perceived bias? Is the original publication highly regarded?
This instantly reminds me of censorship in many countries today. Jamal Khashoggi, a Saudi journalist, was killed in 2018 for his dissident work at The Washington Post. His work was an example of text that broke through censorship. Unlike him, most authors will oblige to how they're told to write. You always have to keep in mind when and where a text was written/published due to censorship around the world whether in a certain region or during a certain era.