I also have blurry PDFs, but I’m on windows 11.
I’ve noticed that depending on the scale of the pdf getting rendered inside the obsidian window bounds, it sometimes renders more clearly. I can nudge it to go from badly blurry to better blurry.
I suspect it is because whatever scaling algorithm is being used works better at certain aspects than others when it tries to approximate pixels. I don’t have this problem with the built-in pdf viewers of the browsers I use.