You don't have to show the Stimulus payment you got or letter 6475 on your tax return. But you have to enter it in Turbo Tax so you don't accidentally try to claim it again.
It is not taxable and you aren't paying it back. Your 2021 return starts out by assuming you didn't get any Stimulus payments so it gives you credit for the full amount and your refund was too high. Then near the end you enter how much you actually got so it only gives you the difference if any. So you don't get it again.
Did you see these screens when you filled out your return? See Critter's screen shots
https://ttlc.intuit.com/community/after-you-file/discussion/irs-notice-error-in-2021-form-1040/00/27...
