What would you do
I'm more curious how this works legally: with "normal" found objects,
you have to report it. If nobody picks it up within a year, you become the new owner.
With crypto, you basically find data, and the original owner can still have a backup. I've never seen a legal case about this.
Good point, I guess the authority who is reported to might be able to ask exchanges if any of their customers withdraw to specific addresses.