There is. Living in California, marginal rates for a well-paid engineer can be 50% and more. Given that you give up half of the money, one's incentive to look for a side gigs and other supplemental income is significantly reduced. Of course, nobody turned down a raise saying "oh, taxes are high so I don't need it", but if additional income involves substantial marginal effort and risk, given high marginal tax it's just not worth it.

How do you figure? If I have the choice of increasing my labor by 20% (by some arbitrary metric, like labor hours per week) to increase my post-tax income by 20%, I might decide that is worth it and go for the higher income. If, on the other hand, I am currently at the top end of my current tax bracket, and the next highest bracket means that my 20% increase in labor will only increase my post-tax income by 10%, I might decide that isn't worth it and thus not go for the higher income.

For some people there is. It's a marginal effect. Every time you alter the tax rate, some fraction of earners will change their behaviour.

Have you heard of the "dead weight loss" of taxation? It's a concept in economics.