As far as I understand it, the issue isn't the tariffs per se, but rather the outright threatening to physically attack Canada. Higher prices don't explain such a large drop, rather it is a concerted national feeling of needing to boycott the US as a whole.

One has to marvel at how the media keeps running cover for Grump, effectively normalizing his actions by talking about them through a lens of as if they are coherent policies that might somehow serve the interests of the United States. While at this point the only real question is whether the guy is an outright foreign agent, or closer to an argumentative recliner-bound invalid with foreign-agent handlers.