Below is copied from FIH rules.
Basically, it is an offence to raise the ball intentionally from a free hit even if not dangerous. Players who continually (more than twice) raise balls from free hits should be penalised.

9.9 Players must not intentionally raise the ball from a hit except
for a shot at goal.
A raised hit must be judged explicitly on whether
or not it is raised intentionally. It is not an offence
to raise the ball unintentionally from a hit, including
a free hit, anywhere on the field unless it is
dangerous. If the ball is raised over an opponent’s
stick or body on the ground, even within the circle,
it is permitted unless judged to be dangerous.
Players are permitted to raise the ball with a flick
or scoop provided it is not dangerous. A flick or
scoop towards an opponent within 5 metres is
considered dangerous. If an opponent is clearly
running into the shot or into the attacker without
attempting to play the ball with their stick, they
should be penalised for dangerous play.