You could work through UpWork for 10 years and contribute tens of thousands of dollars to their profit and they could lay you off forever in a heartbeat based on their policy (after 10 years) or based on a whim of your employer who falsely reports you. If you built your freelance business solely on UpWork platform YOU ARE SCREWED my friend.
UpWork is just another example of evil corporatism. The fact that they make money out of connecting workers with employers for hard cash does not make them any different from weapons producers or oil companies.
They represent the evil nature of corporatism. They care only about their profit.