Gas Giants like Jupiter barely contain any gas https://twitter.com/SusannaLHarris/status/1289573954588250112

Their interiors are mostly made of liquid metallic hydrogen and hydrogen above the critical point... so Gas Giant isn't a really good descriptor. It stems from the fact that they're made mostly of hydrogen and a tiny bit of helium: these are gases at most temperatures on Earth

People end up thinking we could fly straight through Jupiter.

I left you hanging saying "above the critical point". What it means: if you compress + heat gas it will eventually turn to a state which has the properties of BOTH a liquid and gas. It's called a supercritical fluid and it dissolves in things like a liquid but moves like gas

Via NASA JPL. You'll notice there are no diagrams out there which mention the above as it's complex to explain. Also, we don't know exactly where all the boundaries are yet. In this diagram they cleverly point to the *edge* of the outer layer, beneath which is supercritical stuff