I loaded a new game in the latest version of Minecraft (1.20.81 to be exact) and I began eating an apple and realized I was eating regardless of whether I was full. I swapped to a different food item(Cooked mutton) and I could not do the animation or eat it, as I was full already, however, I swapped back to the apple and I did the animation and ate an apple(lost 1 in my inventory).