I bet you're right. This is an obvious one where people will wonder why they aren't paying tax now. I bet you've hit the nail on the head.
And if Labour was holding this one in reserve, it's pretty smart to release it now. National will have to make sure theirs is a little different from Labour's now.
Might be 4D chess. Maybe National were wondering what Labour were planning so decided to annouce that they would soon announce a tax policy so that Labour would show their hand.
The problem itself is not simple, and internationally governments have been wrestling with how to solve the issue. Even this article states they can't implement anything until 1 Jan 2025 because of an international negotiation agreement, but have said the legislation is ready to go if that fails.
Their proposal is relatively straightforward, but I would bet it won't stick around long term in that form. Some company or other will tell the govt they will bring something to NZ if they get an exemption and the govt (whichever is in power) will agree and then suddenly there will be exemptions all over the place.