If you watch Scotty Kilmer's car repair channel he talks about car companies whose quality has slipped for various reasons. He talks about this a lot. He also talks about parts suppliers that can change from making excellent parts to shoddy parts and vice-versa. In the case of car companies he attributes some of the quality problems being caused by a company being sold and being bought by another company with existing dodgy quality processes and culture. He even mentions that Toyota are not as good as they used to be!
Could it be that Boeing has slipped in a similar way to Toyota? (I am not suggesting that Boeing has become like BMW, Nissan, Chrysler, or Fiat.)
Here are three articles well worth a read. The Aljazeera one is similar in content to the B787 video documentary but is particularly concerning in that former long serving Boeing engineers are adamant that schedule has become too dominant over safety and quality.
The other two links are about the US Air Force refusing to take delivery of new tanker aircraft due to tools and debris being left in the aircraft prior to delivery.
https://edition.cnn.com/2019/03/14/politics/air-force-boeing-refueling-plane/index.html