The reason people return the RMDs is that they don’t really need the money, and would rather leave it back in their IRA to keep growing tax-deferred as long as possible. OR they decide to roll it into a ROTH IRA –using money from outside the account to pay the taxes. Then it will grow tax free.
If you took money out earlier this year, and taxes were withheld, you don’t get them back. But you can apply them to any taxes you will owe on other income this year — or against the taxes that would be required for the Roth conversion.