AFAIC it's not anechoic-like for sure: decay in the room exists, although not the same type as in a more "classical" CR, and floor is of course reflective.
I remember someone using the word "Ambechoic" to describe the room (RPG engineer I think). It is an excellent way of describing it.
It is in many ways a RFZ room, based a new way to implement the concept.
One important point: I suspect the very deep diffusors he uses (that go really low, like 100Hz (?) for the walls and 60Hz (?) for the ceiling IIRC) actually do mechanically absorb a LOT of energy in the LF, and a very healthy amount in the MF and HF range. So while they are primarily diffusors, they are certainly used as absorbers too.
They obviously bring a new concept on the table. It sure is amazing.
But unfortunaytely, for 99,99% of the studios out there this is not a viable option/model. Technically and cost wise. And this is clearely very far away from the average living room.
As an extreme design, it stresses the importance of proper diffusion in a room.
I hope I get to visit it at one point