Stop rigid bodies from sinking when standing on it.

I am new to Unity and confused. I read that you should always use rigid bodies on moving objects and use FixedUpdate. Also that you should us velocity or movePosition instead of position.transform.

When it comes to moving platforms I see many people use the update and position.transform functions. Doesn't that cause problems in the physics engine?

I did create a moving platform with a dynamic rigidbody and my character does stick to it. It uses velocity instead of move or transform position. My only problem is that the platform sinks when the player is standing on it. I don't want the weight of the player to affect the Y velocity of the platform. How can I stop this from happening?

I can make it work with transforms and without rigidbodies but it feels wrong intuitivily.