I was more thinking of investing the money on the markets like your bank does with the money in your bank account.
It's never just money sitting in an account, it's an opportunity for some banker to invest money they don't own to get richer themselves.
Honestly think it's almost impossible this money will be returned.
You wouldn't seize that much money to return it years later. It would be essentially an admission of guilt to return it. Nothing to win there politically.
The only scenario where the money could be returned would be if Russia somehow won this war and managed to patch things up with the EU. Very unlikely.