In the Item statistics screen, by default all the items are sorted arbitrarily, and the sorting sometimes changes when the game is restarted. It would be expected that they are sorted the same every time (alphabetically?), similar to the General or Mobs statistics screen.

To reproduce

1. Open a world
2. Look at the Statistics screen
3. Take note of the item order
4. Restart Minecraft
5. Open the world again
6. Look at the Statistics screen again
   → The item order changed (and doesn't make much sense)

It might take a few tries to reproduce. I'm not sure at all what the item sort order is based on. Sometimes it changes the sorting in between restarts and sometimes it doesn't.

The two screenshots show the same world's item statistics, there were no statistic changes in between (regarding item statistics at least).