YSK: Cats don't like their whiskers touching their food bowl. This is why they beg even if food is still left at the bottom.
Whisker fatigue causes stress and overstimulates their senses. Using a flat bowl or plate will relieve this issue and allow your cat to eat all their food without stress.
You can also search for "whisker fatigue" bowls specifically made for cats.
I have a whisker friendly dish and my cat still does this. My cat just likes company when he eats and he’ll meow at you to come join him. He digs in as soon as I sit down with him at his bowl. Just a little weirdo butt.
My cat will come and tap me a couple of times with his paw to get my attention, then wander to his food bowl. He just wants me to pet him while he eats. It's the cutest thing.