Pico-8 is quirky like old consoles. Sprite tabs 2 and 3 share memory space with the bottom half of the map. SO you can use 128 sprites and the whole map (128x64), or 256 sprites and the top half of the map (128x32). This is just warning folks new to Pico-8 that there is a trade-off -- maximum sprites and half the map, or half the sprites and maximum map!
TOY BOX JAM 2 will have a minimum of 512 sprites (and a variety of sfx and music) in TWO carts available. LOTS more assets if you solve the mystery!
Let me know if you have more questions!