Qualified immunity is the principle that a public official acting in good faith cannot be held personally liable for an action that is later determined to violate the Constitution. No reasonable person, other than a nihilist, could possibly disagree with qualified immunity. (For those who insist on viewing everything through a political lens, qualified immunity was first articulated wrt police officers by the extremely progressive Warren Court in an 8-1 decision, the same court that gave us Miranda and struck down anti-miscegenation laws in Loving.)
What many people do reasonably disagree with is the shift in Harlow so that the official is presumed to be acting in good faith, and the person whose rights were violated has the burden of proving otherwise (by showing clearly applicable precedent).
A reasonable person can, and many reasonable people do, oppose Harlow and think it should be overturned. But it is not possible to oppose qualified immunity without also opposing functioning democracy.