It's not that bad. Remember people, Someone worked hard on this for hours. Even if it's generic, it's still something someone made for you to read, and you're not even paying for it. Be greatful.
Okay, i can chalk using 1 small fireball and 1 big fireball costing 500mp since MC probably just got the skill and it is still unoptimized (imagine spam cast small fireball untill it is big).
But getting 500mp from 1 level? That is some broken ass scaling.
i always hate it when isekai series just have the magic system work with just "you just have to use your imagination", it is a lazy way for the MC to just cast whatever the heck he want.