I was doing the coffee cup tutorial that made by Blender Guru,and this happened:
The shadow looks weird when there is liquid in the cup.(Look like dimanods?) But everything looks right when there is nothing inside the cup. Don't know why is that happening. Here is my compositing.(I didn't turn on the denoising in the render properties.) Here is how it looks like in rendered view mode The wireframe of the glass and the liquid.
Have a nice day.