I think the whole problem is carbon fiber is TOO rigid.....and I suspect proper inspections weren’t being done between dives.
Where I used to work we had a whole department that used multiple processes dedicated to inspecting parts for cracks and flaws. I doubt anything like that was being done.
How do you do NDT of Carbon Fiber?
X-ray?.....................
The vid I saw of the hull being built was using a simple lay-up technique.
Monocoqued carbon fiber using heat and pressure to activate the resin results in extremely strong assemblies.
I’ve broken lots of laid-up carbon windsurfing and biking equipment. It all stopped when it started to come as a heat and pressure molded assemblies.