Boeing Whistleblower: Production Line Has “Enormous Volume Of Defects” Bolts On MAX 9 Weren’t Installed::A reader at respected airline industry site Leeham News offered a comment that suggests they have access to Boeing’s internal quality control systems, and shares details of what they saw regarding the Boeing 737 MAX 9 flown by Alaska Airlines that had a door plug detach inflight, causing rapid decompression of the aircraft. The takeaway appears to be that outsourced plane components have so many problems when they show up at the production line that Boeing’s quality control staff can’t keep up with them all.
People who know more than me have pointed out that the the hole in the fuselage and the plug found on the ground don't show the kind of damage you'd expect if the bolts were present and secure.
So them being absent entirely is consistent with the publicly available evidence.