Will I have any problems with this?
Yes.
Not only can you account be removed.
Depending on how far the author of the art is willing to go.
He may press charges and take you to court for "damages & lost revenues etc"
So you may end up having to pay a hefty fine for breaking dmca etc laws + having to compensate the author.
Is it worth taking the chance ?
And then we have the moral part.
Dont try to earn money on other's work.
Use the work as a learning tool, use it as a resource for expanding your knowledge but dont use it in any public scenarios to make $..
Make your own art. or use AI to help with it or get a 2D artist involved who knows pixel art
Simply said: it is never ok to steal anyone's stuff, there is never an excuse or reasoning for it.
Robin Hood disagrees
But yea i in general agree with this. there is a big difference between dl a pirated software from a big firm and stealing an artists work who just tries to getby.