Oh, please. Let's not go there. Epistemologists have never suggested or promoted any such thing, your wariness is misplaced, it seems. If anything, fascism will use any and all rhetorical resource to promote their rise and stay in power. Remember, before post-modernism—which is the source of the "every person has their own truth" thing you dislike, not epistemology which predates post-modernism by a couple of centuries—fascism used objective truth as justification for the superiority of the in-group in power. Eugenics was touted by fascists in the 1800s as the epitome of scientific enlightenment. It was obvious and proven scientific knowledge that black people were an inferior race, etc. All the classical Nazi pseudo-arguments. A harsh and closed view of objective truth is precisely the kind of mindset where fascism thrive. Fascists like absolute truths quite a lot, even when they contradict each other.

The point of epistemology is to analyze the ways in which humans come up with and use knowledge. It has absolutely no prescriptive tenets at all. It is entirely descriptive.

Like, you can't look at me in the eye and seriously suggest that Bertrand Russel, Jean-Paul Sartre, Locke, Hume or Immanuel Kant were fascists.

Yeah especially about things that are considered fundamental like the physics of fluids.

Unless they’re arguing about some quantum effect that hasn’t been proven maybe, but then they’re either a physicist or a Feynman bro who thinks they figured it out after “thinking hard about at and watching 7 hours of YouTube videos”.