Just blame shrinkflation

Some of the pieces are growing, but it’s cut at an angle so the growing is spread over a large area, and the growing happens as pieces are moving around, making it hard to notice.

(Specifically it’s the pieces 2 and 3 wide with an angled cut on the bottom that grow).

The gif is kinda misleading. The volume of the chocolate shrinks when you do this trick. You can actually notice some is missing. Mostly because it's cut in a weird way

No longer a mathematical problem, but determine the largest piece that can be removed, before it becomes apparent to onlookers that the leftover pizza has been tampered with.

You're probably mozzarella