To clarify, did you parents claim you as a dependent on their tax return last year and this year you will be filing your own return? Additionally, if you are filing your own return, will your parents be claiming you as a dependent on their tax return?
If your parent's are not claiming you as a dependent for the 2021 Tax Year, then you will say "No", since it is your parent's who received your stimulus payment and not you. This way you will be able to get the stimulus payment added to your refund.
If you were a dependent on a 2020 return but filing independent for 2021 you can get it now and they don't have to pay it back. So say NO you did not get one because you didn't one, your parents got it.
The 3rd Stimulus payment is really based on 2021. The IRS just sent the checks out using 2020 to get them out fast.
See IRS Topic B first question