Yes, anything, really. As far as I know, he touches upon the theme of dark medieval times in almost all his books. You could choose The Witcher, for example; it's a good book, well-known, and there would be plenty to discuss with others.
The book is excellent. There are plenty of writers in this genre. But it's still dark fantasy, not medieval times.
And regarding the depravity – yes, that's 100% true. What used to be considered a disaster for the honor of a normal person is now completely normal. People actively exploit each other's base instincts for selfish purposes and don't feel ashamed about it. It seems like everything is allowed... for a certain price, of course.
Honor? Take any example of this "honor," whether it's a knight, a samurai, or a gentleman – they didn't always adhere to their own invented codes. And the majority of the population has always consisted of people from lower social classes, who were often not very familiar with the concept of honor.
For example, the idea of a knight as an ideal of honor emerged at the end of the knightly era, along with chivalric romances (here, Cervantes should be mentioned). Initially, "knight" was equivalent to "cavalryman," and later also "small landowner."
An important source of misconceptions is school history textbooks, which not only don't always tell the truth but also often omit details. Does Rasputin's biography mention what Boney M sings about? Does the textbook mention that in any medieval army, traveling prostitutes accompanied the baggage train?
Many more examples can be given to prove that the level of depravity has not changed much. We live as we did in the Kali Yuga.
Наше оружие - неожиданность! Неожиданность и страх, страх и неожиданность - это два наших оружия! Плюс безжалостность - три наших оружия: страх, неожиданность и безжалостность! И ещё фанатичная преданность Папе - четвёртое! Наше оружие включает в себя... наше оружие включает в себя... страх, неожиданность... я сейчас!