Talking heads inside that box told me that Canada complained to the WTO claiming USA and Mexico were discriminating against them because of labels.
The next part is a bit fuzzy - the talking heads told me either Canada wanted to impose billions in punitive tariffs to make up for whatever losses the discrimination caused, or Canada wants to impose billions in punitive because of the losses the discrimination caused.
I'm not all that concerned by all that lead in foodstuffs coming from PRC. It's all the other stuff.
stay safe.