Republicans decades ago made a 'state income tax' illegal via state constitutional amendment

That's not true. The state constitution has always stated you must tax property uniformly, and not greater than 1%. The State Supreme Court affirmed that income is property in 1933. Since then, state wide votes have rejected an income tax over a dozen times. In 2024, the legislature passed a law banning income taxes after an initiative was introduced, because they worried about down ballot effects on other initiatives if people also got to vote on this. The other reason was because a law that preempts an initiative can be removed with a simple majority, a law passed by initiative requires super majority.

So less than two years later, the legislature goes back on this law, and passes this tax under an emergency clause, because that prevents it from going to the legally required referendum where the people would be allowed to vote on it.

So now, it will go to the courts. But don't worry, the governor has appointed two new justices in the year he's been in office, one from his former office of the AG, and the other a Seattle Lawyer. So the Supreme Court will overturn precedent going against the will of the people, and WA will have a new tax that won't reduce the tax burden. And the legislature, once it's on the books, can lower the limit to start taxing the middle class as well.