I can say this about that. If you have not worked in a mold shop, or run molding presses, or don't have direct knowledge of molding equipment, I could see where you may not be able to understand the process. These shells are made in a factory, maybe more than one factory, maybe by outside contractors not directly owned by DJI (this scenario is very likely since the demand is high). They are also made on more than one press, most likely several in each shop. Each machine has its own settings (and they can be finicky) and white parts are a real pain to run. The shop or shops may have a good supply of resins, or maybe they order from several suppliers leading to variations. Many different conditions can affect the final part. Parts are sampled at the start of a run for approval on each machine at each startup. Then again periodically throughout the run. The machines making these shells may be run by a human operator, or more likely a robot. If a problem is not detected right away, they might make quite a few before the run stops for corrections. The shops making these for DJI may send some of those parts out either knowingly or unknowingly. Now there are bad parts in the wild. DJI stepped up and took responsibility and let buyers know if they have an issue to let them know and they will replace it. Now we know DJI recognized the problem and changed the design. So was it a bad run of shells, bad design, or both?
Someone mentioned Apple. Apple has had many issues in the past that they took forever to recognize as a real problem (antennagate anyone?). When it becomes inevitable they step up and do the right thing. Companies will try to cover their bottom line. You can bet this is costing DJI a fortune to correct, just in mold redesign alone.
Hopefully you never have it happen to yours, but if it does, send it back and get it fixed.
There is lots of companies coming up so if DJI wants to keep its edge they will have to keep improving or get passed by the competition.