Alright, after feeling like a retard with 291h because it sucks with hires fix (and img2img and inpainting and adetailer) I decided to do some testing
Here's an image that I did on 219h and then upscaled it, which gave me a completely different image (running into the same conundrum of the previous thread: it looks blurry and shitty if it's low denoise, and it changes the image while adding little detail if it's high denoise). Then I kept the same settings, changed the model to madlymix (the one I normally use, it's pretty analogous to WAI NSFW) and upscaled it again, and it gave me a great result.
Why is 291h like this?