Sounds like it might have a CVT.
Or direct drive? Fewer parts, less weight, lower friction loss. Maybe they figured out how to make a high torque low rpm motor thats still small & light?
I'm 90% sure the Plaid powertrain uses direct drive permanent magnet motors, i.e. two "hub motors" integrated directly into the rear wheels, eliminating the fixed gearbox, axles, drive shafts, etc.
(Front motor would still use gear reduction and a differential I suspect.)
Direct drive has numerous advantages, the primary one is to shift the torque curve to the left massively, enabling maximum torque at high speeds as well.
On the Nürburgring high speed acceleration is perhaps the most important factor.
Tesla's drive units are good up to 20k rpm I believe - with direct drive that would support speeds up to 1,000 mph ...
With direct drive there should be flat torque output up to the ~400 mph max speed of the Roadster 2.
Another big advantage would be very good, very direct torque vectoring.
The challenges would be ripple torque at low speeds and cooling: if the motors are part of the suspension then any coolant would have to enter through durable yet very flexible pipes. Plus a lot of challenges I don't know about - if it was simple everyone would be doing it.