Even in a snap election mandate, they'd just make the donation now—it's highly unlikely there will be a snap election in the next year—and this would allow one voter to donate millions to several interest groups, knowing that they're going to spend it during the election in a way that this voter likes. Then, they themselves could spend millions of their own during a pre-election period—up to the two months if it were a fixed election—right up to the election campaign period, and then spend $1.6 million. The only disclosure would be of the $1.6 million spent, or, if it's a snap election, only $630,000 of the spending. All of the rest of the spending would be done by someone we don't know, and there would be no disclosure of that. Again, the U.S. rules are much stronger in terms of disclosure during an election year.
