The fish rots from the head.
Boeing management used to listen to their engineers. Some time in the last 10 years or so they got a new CEO who has publically bragged about firing all the "assholes" that told him "no." Meaning the White engineers that didn't want to take shortcuts.
The result was the 737Max. Essentially, it's just a standard 737 fuselage, but they put new, high-efficiency engines on it.
No big deal, right? Wrong, the new engines, in order to be more efficient, have a much larger bypass section. That's the front of the engine where air comes in. Basically, it just uses a big fan to pull some air into the engine to create a hot exhaust, then pulls even more air around the engine, mixes it with that hot air and creates more thrust.
The problem was that the new engine was so big that it no longer fit under the wing. The only way to get it to fit was to modify the engine mounts so that the new engines sit way in front of the wing.
This causes a problem, though. The new design moves so much weight so far forward that it upsets the basic stability of the aircraft. That stability is recorded in the original 737 airworthiness certificate from the FAA.
Well, the new design would need a complete re-certification. That would cost billions and gut any savings making the new plane un-sellable.
So the new, non-asshole engineers just rewrote the flight computer code to compensate for the moved weight, making the airplane not allow the stick to move in certain ways and ignoring pilot input under certain conditions.
But they didn't foresee all conditions, and several 737Max planes got into a condition where those changes basically caused the airplane to stop flying and crash.
Of course, rather than admit guilt immediately, fire the non-asshole engineers and re-hire the asshole engineers that told the CEO NOT to try to do this, he just doubled down and started implementing DEI.
The current problem exists at the end of a timeline that started with people that don't know anything about what Boeing actually did be allowed to run the company. And run it they did. Right into the ground. Next to several 737Maxs.