Ros publish rate is different from simulation step rate

Hi,
I have a question about Isaac Sim ros publisher.

Why ros publish rate is different from simulation step rate?
I write a while loop, inside each loop, I ran ros publish.
I recorded the delta t, which was basically 0.01666 i.e. 1/60, 60 hz.
But when I use rostopic hz to check the publish rate, it is 160 hz.

the code I wrote is like this:

while simulation_app.is_running():
            rospy.publish(msg)

Can you give us the minimum code to repro this please? thanks.