The global wealthy can afford convenience and excess while the global poor can't afford basic needs. As such "it's just in the wrong place, so it's cheaper to throw away" is a desired outcome for the wealthy not a problem triggering inefficiency. It's also best to not equate food usage efficiency to general efficiency as a lot of the excess is the result of more food being cheaper than efficiently consuming less food. E.g. growing 100 apples to have 100 actually consumed apples takes a lot of effort to make happen. You have to make sure none go bad in transport, all are immediately sold at the store, and that people heavily plan out their lives around eating every apple they buy before it goes bad. It's just more efficient as a whole to make more apples even if that makes food efficiency look worse.

Carrying that forward whether or not there is a "global shortage" (taken to mean not enough produced for everyone to not go hungry) is irrelevant. People are already going hungry today so "enough that everyone can be fed" can't be the controller of why the wealthy can afford excess. The ability comes from their production and purchasing power compared to the world not the overall averages of the world.

Of course simple economics still exists and less of the good will result in a raise of price, the question of course being how much not working from decreased consumptions backwards. That raise in price is only proportional to how much is needed to lower global consumption. It's not a guarantee the wealthy will notice enough of an impact to no longer be able to afford excess. In reality the poor that were already short on food will see a bigger decrease in consumption than the wealthy due to price increases. A 10% price increase in food is only inconvenient for most in wealthy countries but in poor countries many have no choice but to consume less food as they have no more money to spend on it.

If I had to guess this shortage won't be near enough for production to be less than ideal distribution coveraging hunger. That said it'll still affect prices, just probably not enough for wealthy countries decreases in excess to have a meaningful impact on the overall supply.