Can someone explain the credit?

# מהמקור

I am on the $20 plan - I thought these $20 were the ones I was allowed to spend on "Other Models", however after reaching 100% on other models this "Credits" tile popped up, is this the actual $20 limit? And if so, why is it $25 in the $20 plan? It's confusing me <a href="https://preview.redd.it/n5qzc721hjlh1.png?width=1122&format=png&auto=webp&s=40ade2a39f8fca3d203a4eccbaf6ebe