It’s literally in the book. Harry becomes a wizard CIA agent. They still have slaves at the end. The book ends with Harry wondering if his chattel slave will bring him food. They don’t help the muggles, they don’t rectify the injustice of their tiered society.
I think the anti fascist angle is a nice thing to get from it but it’s not really supported by the text. Riddle is ontologically evil for no reason, he’s bad Dumbledore. Dumbledore controls the entire society and can act with impunity. I don’t even think all this stuff is intentional. It’s just not that deep.
For sure, there’s an unhealthy internet thing of just hating stuff, I hope it’s obvious I’m not doing that. I actually think the books for younger kids are overall better and a lot of the worst stuff could have been avoided if she just stuck to writing fun mysteries for children. She was pretty good at snarky irreverent kid stuff.
The biggest fans in my life hate the epilogue too, so you’re in good company there.