tl;dr: PostgreSQL 19's beta saw an unusually high number of feature reverts (8-10), largely because LLM-assisted code review and fuzzing surfaced many edge-case defects that previously would have trickled in over years, effectively raising the quality bar faster than older in-progress features could meet. Compounding this, senior developers were tied up with security work ("Vulnpocalypse"), leaving less time for beta review and fixes before the release deadline. The author suggests the community should invest in more robust internal interfaces and a mechanism for landing features as "experimental" to mature in-tree.