The spike in 2021 had nothing to do with tariff rates, it had everything to do with the lockdowns shutting down "non-essential workers." https://www.woodworkingnetwork.com/news/canadian-news/coronavirus-forces-curtailments-four-major-canadian-lumber-mills the same thing happened with oil but for different reasons, there was a massive glut and the prices went negative since demand was cut so dramtically, so huge amounts of wells were shut down. The lockdowns were one of the most shortsighted idiotic things ever done to an economy and the boomerang effect clubbing people in the face should have been expected.