I think price-gouging laws could also have something to do with this. Suppliers have increased their prices in what is essentially protracted inflation from demand. But in most states retailers are not legally allowed to increase price tags which was triggered in March when most states entered a state of emergency/declared disaster [1]. So the results is that retailers have to stop stocking these or they lose money; and the increased demand doesn't fully reach suppliers which means that in turn, manufacturers have also less incentives to increase production.

[1] https://www.natlawreview.com/article/price-gouging-laws-and-...