Very quick video of what happens.
For now, if I conside that a catastrophic implosion - occured, there is certain gear of the submersible that floats, and that gear is not within the submersible capsule.
There is a chance that at least one of the large, bright orange, inflatable buoy devices would get clear, inflate automatically and make its way to the surface.
And probably some other gear would make its way to the ocean surface.
So, if an implosion took place just after 1 hour 45 minutes during the descent, I would expect that some debris would show within an observable surface area.