When cats do this (complain that the bottom of the bowl is empty), it's typically because they don't want to shove their face (and wiskers) into the edges of the bowl
Its called "wisker stress"
A shallower bowl (or just a small plate) is usually more comfortable for them to eat off of
Alternatively, they might paw the food out of the bowl then eat it off the floor, for the same reason
It's not entirely true. I use a simple plate, there is no bowl, and she still begs when she can see more of the plate than she would prefer.
I think they just like to know there will always be enough food even if you have a routine. I feed my cat at 7am and 5pm but she acts like the next feeding will never come lol
I feed my cats their wet food on large plates the size of dinner plates. The assholes still prefer to paw it onto the floor and eat it off there, and then leave a mess everywhere. They get their kibble in a wide shallow bowl, and that stays in place.