Huh, my Facebook feed is all about feminism, animal rights, and glurge. And I am not at all into that, but I guess many of my friends are, so that's what I am shown. I have a few "right wing" friends, but they are a minority, so I rarely get content like that.
It is just a bubble, it doesn't look like Facebook has any kind of bias, except to the best paying advertiser I guess.
It actually makes Facebook less "bubbly" for me. I get a variety of opinions that aren't mine, they are often controversial (controversy drives engagement), but rarely violent. Twitter and YouTube are much more targeted.