One reason is that the food supply system is comprised of retail and commercial sectors. The commercial demand collapsed as restaurants & institutions closed, while the demand at the retail level skyrocketed when people panic-shopped.
The packaging needs of the two sectors are different - retail packaging must have the nutrition & ingredients panels on it, while commercial packaging would typically only have it on the carton.
To add on to this, the supply chains/logistics are somewhat different as well on top of already-stressed delivery infrastructure, so there are multiple bottlenecks in getting food to retail shelves. When demand skyrockets without warning (like it did), it's not really possible to immediately scale up, so you get shortages like we're seeing and thus food prices go up (temporarily) like you would expect.
The packaging needs of the two sectors are different - retail packaging must have the nutrition & ingredients panels on it, while commercial packaging would typically only have it on the carton.