Global News reports
In March, the masks sold to China in January and February were being sold back to Mexico at 20 to 30 times the price, according to [Jorge] Guajardo [Mexico’s former ambassador to Beijing].
There doesn't seem to be much doubt regarding China's imports in that period at least according to China's own official customs' documents.
But were [some of] these stocks sold to Mexico and at 20-30 times the price thereafter? (And was this a significant quantity being resold at such high markup, to make the claim more than nominally correct? Note that the claim say "the masks", as if all of China's earlier imports were [being] resold to Mexico, but the claim is almost certainly false if read that way.)