I don't know exactly how it works, but the gist of it is your "US income" and your "Indian income" will both be taxed by the US, in addition to the Indian government taking their cut. In 2021 you could deduct up to $112,000 from your foreign income to be taxed. Taking a simplified scenario:
Let's say you made $150,000 during your time in the US. You're on the hook for income tax on that amount.
Now, you fly to India. You make another $150,000. Well, theoretically that's subject to both Indian income tax and the US foreign income tax (there are of course deductions/country laws that affect this, but the general idea holds true). Let's say you deduct the full $112,000 from the income; you're on the hook for tax on the the remaining $38,000. So your taxable US income would probably be $150,000 + $38,000 = $188,000 (but I don't know how the math exactly works out). As long as India is concerned, your income for that year was $150,000 in India. You also need to pay them their cut.
This is a hell of a lot more complicated (and probably more $$) than just being taxed for your $300,000 in the US. And this is ignoring all the equivalency sh** you probably have to do to practice in India as well.