I mean seize illegally earned money and/or forbid them and their families spending those money in the EU and other friendly jurisdictions. EU as a whole should have enough weight to make it happen if enough political will is present.

They are already forbidden to conduct any business, i.e. spend any money, in the EU.

To literally "seize" the money stored in an offshore bank account is difficult unless the EU is also willing to march an army into those countries.