"Loss of motor control" rule by AIDA.

"Post-Blackout Mechanical Movements are characteristic, physical movements occurring during short successive losses of consciousness.

There are two types, which can clearly be observed after a freedive.
The first type is a series of short jabbing or stabbing movements of
the hands. As this movement can be hard to distinguish from the typical
shaking hands of an LMC, it will not be used as a reason to disqualify
an athlete.
The second type of movement is a definite and clear dropping or nodding
of the head
as an athlete loses and regains consciousness over and over
again. It is as if someone is flipping a switch on and off. Nodding or
dropping the head just once will not be considered a disqualification,
because if there is a doubt about the blackout the decision has to be
in favor of the athlete. However, if an athlete repeatedly nods or
drops their head they will be disqualified
Important: Even if an athlete manages to correctly complete the Surface
Protocol within 15 seconds while falling in and out of consciousness,
they will of course be disqualified."

AIDA International