Not changed my mind (on what? "The holocaust is bad"?) but Night (and its sequel Day; I haven't read Dawn, which comes in the middle, yet) by Elie Wiesel. Horrifying, but important. Note that it's semi-fictionalized.
On truly changing the way I thought of something, I'd say some of Cory Doctorow's writing on Pluralistic, namely on if enshittification was a necessary consequence of the SEO spammers or a conscious choice by Google to increase.
Finally, Lies My Teacher Told Me. It's about how textbooks (in the US at least) misrepresent history, and how many of them still teach things effectively from the 50s. It's great. If you struggle with context and/or comprehending it (it's written fairly academically), he has a young readers edition (actually I'd recommend it anyway; it's good and young readers editions often provide more context than the 'adult' versions)
