I can confirm that driving the Lambo, it’s a case of when the wagging backend is going to kick in not ifSingle set of softs doesn't work for one hour, especially in the Audi which tends to wear rears at a much faster rate. Because of that uneven wear, the car balance shifts toward oversteer as time goes. This was what likely caused your issues by the end of the race. Driving a car with low grip all around is one thing, driving one that has no grip on the rear is another.
But then again, Brian does seem to do well with the Lambo