For example here is an article from May of last year [1] about a quality issue with Spirit that had been going on for 4 years. Here [2] is one from last October which says "The goal of the agreement is to stabilize Spirit’s production system, by stemming the flow of quality defects that have afflicted the 737 MAX and the 787 Dreamliner jet programs this year and positioning Spirit to ramp up to Boeing’s planned rate increases." The agreement was Spirit running out of cash and Boeing swooping in to save them despite their poor quality, because they were the only supplier for these fuselages. The financial times wrote a good article about it [3].
This is absolutely a story of outsourcing gone wrong. But they didn't outsource it to China or Mexico, they outsourced it to Kansas, USA.
1: https://theaircurrent.com/industry-strategy/boeing-spirit-re...
2: https://www.seattletimes.com/business/boeing-aerospace/boein...
From what I've read, this is not what happened for the door bolts.
The New York Times report was that Spirit required access to some part of the fuselage masked by the door but did not work on the door. The Spirit request was granted, so Boeing workers removed the door, Spirit workers did what they intended to, then Boeing workers put the door back. There is a entry in the maintenance log of the plane about this. There should have been a routine check after this operation, but there was no mention of it in the maintenance log.
This seems like a good time to mention that Airbus also uses Spirit AeroSystems.
Boeing's problems is because B737 Max manufacturing is a job creation program for rural American white men in places like Kansas.
Meanwhile Airbus manufacturing facilities in modern diverse cities like Hamburg and Toulouse have somehow figured out how to manufacture modern safe planes.