I wrote earlier that the accident cause was chassis failure, not aero per se. However after further reflection and watching linked video, aero played an unintentional role possibly. As mentioned, the rear very high mounted wing past the rear axle axle centerline, provides huge DF, and with that, a large degree of drag, which then acts as a big lever arm to lift the front end. That lift is counteracted by the front wing, and we get arch. However as the arch increases, the angle of attack of the rear wing decreases, DF decreases and drag decreases. However the opposite occurs with the front wing, as drag increases, and if front wing lowers lowers below the COG, it's kinda like butting against a concrete wall, increasing the arch, but I suspect the biggest aero contributor is the front wing being in front of the front axle centerline, also acts like a cantilever, and as the front wing lowers, its angle of attack increases with the above mentioned results,more DF and drag, but most importantly, it is now low enough for a "ground effect", with the resultant massive increase in DF. You can see slightly in the video the front wing is on the ground at chassis failure. I'm just winging it here, pun intended.

From Wiki:
"Theory[edit]
In racing cars, a designer's aim is for increased downforce and grip to achieve higher cornering speeds. A substantial amount of downforce is available by understanding the ground to be part of the aerodynamic system in question, hence the name "ground effect". Starting in the mid-1960s, 'wings' were routinely used in the design of race cars to increase downforce (this is not a type of ground effect). Designers shifted their efforts at understanding air flow around the perimeter, body skirts, and undersides of the vehicle to increase downforce with less drag than compared to using a wing.

This kind of ground effect is easily illustrated by taking a tarpaulin out on a windy day and holding it close to the ground: it can be observed that when close enough to the ground the tarp will be drawn towards the ground. This is due to Bernoulli's principle; as the tarp gets closer to the ground, the cross sectional area available for the air passing between it and the ground shrinks. This causes the air to accelerate and as a result pressure under the tarp drops while the pressure on top is unaffected, and together this results in a net downward force. The same principles apply to cars.

The Bernoulli principle is not the only mechanic in generating ground effect downforce. A large part of ground effect performance comes from taking advantage of viscosity. In the tarp example above neither the tarp nor the ground is moving. The boundary layer between the two surfaces works to slow down the air between them which lessens the Bernoulli effect. When a car moves over the ground the boundary layer on the ground becomes helpful. In the reference frame of the car, the ground is moving backwards at some speed. As the ground moves, it pulls on the air above it and causes it to move faster. This enhances the Bernoulli effect and increases downforce. It is an example of Couette flow."