Nothing is owed. The mint deposit has not changed, so no wallet has overpaid.
Minting a DataCenter burns a flat 100,000 $BXT plus a 0.5 ETH surcharge. That deposit has been the same for every mint, so no one has paid more than anyone else and there is no difference to give back.
If the protocol ever lowers the deposit, wallets that minted at the higher price would be owed the difference, and every settlement would be listed here with its transaction. The rules that govern that live in the docs.