About prejudices in historical fiction

I often notice while reading that there is a relatively small bit of authentic historical prejudices I can allow a protagonist possess to remain interesting and likable for me. Surely, when we are talking of historical fiction or fantasy, it is always a problem, how many of their epoch’s prejudices protagonists can have. And where the boundary of plausibility lies, I mean, so that the hero doesn’t look “a Connecticut Yankee” in their epoch.

We know that every historical age has its defaults (and ours does, too), and the things that were ok in the 19^th century are not always acceptable for us now. We know that each age actualizes in historical fiction its requests and pain points so we should in general discuss any “historical authencity” in fiction with a bit of causion (really, I can not say if we have ever read about, for ex. "true Middle Ages" and not about the author's proections on the Middle Ages). Nevertheless, the protagonist which has our attention probably should probably be a bit of an “alien”, for example while living in Middle Ages he/she shouldn’t believe in Jews being evil and so on. Surely not everyone then was that stupid or superstitious, there were always people who didn’t think acceptable to beat their wives or despise Jews; and the authors often invent “the best representatives” of the epoch to be protagonists.

Surely there are things I cannot forgive a protagonist even if they are initially depicted as nice; but if later on I see they are, for ex., racist or, well, up for slavery, it is difficult to lilke them. But reading a historical fiction or a fantasy book set in medieval times I think I would like to have a bit of a true reflection of the epoch, not to see my own modern face in the mirror each time I take a book written by a modern author. I read an article by A.S. MacLeod "Writing Backward: Modern Models in Historical FictionWriting Backward: Modern Models in Historical Fiction" (it is quite old, 1998, but still provokes vivid discussions in the field of children's book, pedagogy, presentism, historical empathy, etc.) and thought that it is the very thing I feel reading K. Cushman, T. Pierce, N. Novik with her Uprooted: give me a little more medieval, not some stereotypical superstitions and beliefs shared by literally anyone... exept the protagonist.