It’s called self-employment tax: https://smartasset.com/taxes/self-employment-tax
It’s not actually a separate tax. Normally your employer pays these taxes but you don’t see it. When you are a contractor you are self-employed, so as an employer of yourself you have to pay these taxes like any other employer.
Some people play games with certain corporate structures where they pretend they’re only worth a fraction of what they’re getting paid and then they extract the rest as dividends. It’s one of those tax tricks that works as long as nobody ever looks to closely at your tax returns, but if you’re caught you have to pay it back plus penalties.