The companies employing the fact-checkers. One company I am aware of is employing right wing propagandists to fact check, to make sure they get the “facts” they want.
Were that even true, there are so many multiples on the conservative side for every one on the liberal/moderate end. Sen. Menendez the most recent example of a democrat held accountable, not protected, by the party
This was much the same in the late 1800’s, then in 1901, Teddy became President and he turned things around.