If you read the parts where they mention “buffeting” that’s the dangerous part, where uneven airflow introduces instability, causing the airframe to rattle.
Buffeting occurs when the soundwaves of the noise of the craft and its motion directly affect the air as it flows across the surface of the plane.
This happens as the plane enters the shockwave of the sound barrier, and ceases when they accelerate beyond the speed of sound.
At and beyond Mach 1 the buffeting is behind the plane, and flight is smoother, with no rattling or shaking from the incidental turbulence.
It also happens when decelerating, although it’s easier to decelerate safely through the buffeting quickly, since less time is spent in the shockwave, and a reduction in speed grants improved control.
