No fixes should be “mandatory” as such, but it depends on what your state laws require you to fix legally before selling a house or renting it out to someone. A home inspection can come up with many issues, which include structural as well as mechanical issues and ones that need regular scheduled inspection and maintenance.
Some fixes to be done to make a home safe to live in and these include excessive mold, railings on stairs, bedrooms with no ventilation, high radon levels, broken walls, and gas leaks. However, these aren’t “mandatory” unless your state laws require them to be so and laws differ from state to state.
The question only arises because one wants to know who is to pay for them and that depends on the arrangement the buyer, seller, and estate agency has. Of course, if it is about a place for rent, then it depends on the state laws and any disclaimers issued by the rental organization.