Qualified Immunity is US case law precedent, which means the courts basically are applying existing laws to novel situations to make new laws (Harlow v. Fitzgerald.)

Initially, courts ruled that the police lost qualified immunity if they performed an action that they knew violated peoples rights (Malley v. Briggs)

Lately, courts have basically said "how could the government know it was a violation of this guys rights? Sure, there is a very similar case which said you can't violate this right, but the details are slightly different, so how could they know the persons rights were protected in this specific case? Case dismissed." (Zadeh v. Robinson)

It's absurd, not just because the details are always different, but because the initial case law was set without any similar precedent. It basically takes a particularly egregious violation of your rights to overcome the qualified part of qualified immunity and sue the government (Taylor v. Riojas)

(Not a lawyer, but married to one.)