Nothing burns trust faster than a blameless postmortem with a hidden defendant.
The anti-pattern is simple: importing the agenda from a high-trust team into a low-trust one and calling it culture change. The form looks right. The substrate is wrong.
If people know the real consequences arrive later—in performance reviews, staffing decisions, or the next quiet exclusion—they will not tell you the truth in the room. They will perform. The meeting becomes theater. Real learning moves to side channels. The next time leadership asks for candor, it gets less.
Trust rarely breaks all at once. It goes cold, then quiet, then expensive.
A hard boundary: when was the last time a junior person contradicted a senior in public and got safer, not smaller?