Similar event here :
https://assets.publishing.service.go...XWBC_09-22.pdf
The root cause to me appears clearly on the plots page.
The elevators show a clear triangle shape. This means the elevator are chasing a target they can't reach, at maximum speed. This basically means PIO.
Why is there PIO ?
Because the pilot pulled, and noticed a reaction that was too large. He was convinced that the reaction was too large especially when the tail hit... So he pushed forward at maximum, and induced the PIO.
Why did the pilot pull too much ? Because if you look closely, there is a huuuge delay (in the order of one second) between the pilot pulling and the elevators going up.
So the pilot maintains his order longer than he would have, if the plane had reacted. It can also happen that when noticing the absence of reaction, he increases his order (maybe not the case here? look at the curves and see for yourself!). If he maintains his order, the time average of the order that is used in the flight control computer will increase and the elevator will go nose up... Too far nose up. Hence an airplane overreaction, and the subsequent induction of PIO.
Here, with only two full triangles visible, it's a short PIO. But the PIO is just a symptom of the PIO conditions being present. And only the onset of PIO, which is an airplane overraction, is enough for the plane to strike its tail.