My assumption is the bias is unintentional, at least partially, and just the priorities of recommendations is weighed heavily to encourage engagement above all else, and stoking fear and anger drives engagement. Also the distribution of content could be a factor. On the right, it seems like everyone is trying to get in on the grift of advertising elk meat or trump coin to exploit their viewers, meanwhile high quality journalism and news is under funded. For every Climate Town or A More Perfect Union, there’s tens or hundreds of right wing fearmongering videos.