There is no good reason for the Covid-19 pandemic to cause food shortages, at least of wheat, rice, or other staples. The virus isn’t foodborne. Plenty of food continues to be produced, processed, and delivered despite illnesses and lockdowns, and the world’s appetite hasn’t abruptly increased.
There is, however, one bad reason for shortages: hoarding. If some people needlessly buy too much food or sell too little of their production out of concern that there won’t be enough, others will lose out. Look at what’s happened with toilet paper supplies in parts of the U.S.