The aircraft was travelling at excessive speed; in excess of VMO. That is acceptable if you are on fire and heading for Nice or somewhere like that. This aircraft remained on track.
Travelling in excess of VMO in a A320 disconnects the AP and triggers the high speed protections which pitch the aircraft up. This aircraft did not pitch up. Which probably means it was being over-ridden by whomever was flying it.
That raises the possibility that the aircraft was hand flown all the way down.
Are you
certain the aircraft was flown above VMO?
The only analysis I have seen was someone did a quick calc, and showed the aircraft at, or slightly above VMO. Their data (they said) did
not include allowing for wind, and the wind that day (they said) was southerly.
If that is true, it raises the prospect the aircraft was flown at/close to VMO using normal AP modes?