Create a simple app as follows:
Start the app and create 11 Pizzas. Click the "List all Pizzas" link and you will correctly see this:
Go to page 2, and you will correctly see this:
Click the "15" link, and you will see "No Pizzas found". A power user might realise from that link's target URL that the list is empty because it's displaying page 2 with a page size of 15, but most users would be surprised to see an empty list. Instead, they would expect to see all 11 pizzas on a single page (I hallway-tested this theory on some non-technical colleagues).
In general terms, increasing the page size will wrongly show an empty list when the new page size times the current page number exceeds the number of available results. The only way to provide consistent, unsurprising behaviour is to go back to page 1 when changing the page size, as the page numbers that correspond to the previous page size no longer make sense.
P.S. When testing or replicating this, please be aware of the navigation problems caused by