“So a case with the same set of facts in the 5th Circuit that overcame qualified immunity would not do so in any other Circuit.”
When conflicting decisions like this occur in the lower courts, it is the job of SCOTUS to take a case and render a decision that brings ALL conflicting decisions in the lower courts under a unified ruling. Thus, further decisions by the lower courts should be able to render a ruling consistent with the SCOTUS ruling.
The problem is that in the majority of cases, no decision is ever rendered on the facts of the case, because the case is dismissed on the basis of qualified immunity, so it never gets to a level where SCOTUS will even hear it. That is the main problem - the cases get dismissed because there is no applicable precedent, and no precedent ever gets established because the cases get dismissed (because there is no precedent...)