Gravity effect on deaf people

It’s due to the fluid in the inner ear, if I’m not mistaken. I’m guessing their system can’t “detect” how the fluid is moving. Sloshing the fluid rapidly is why we get motion sickness, or even why we become dizzy. So, the deaf people would be immune to gravity affecting that fluid.

If the fluid is for knowing which way is up, what does it have to do with hearing?

I guess it depends on why the person is deaf, but I assume it's because the deaf person is not receiving any information of any kind from their ears. Typically, we assume this just means hearing. But that also means not receiving the information from this fluid-hair system we use for balance.