User blog comment:CartoniAnimatiMania/Luna Loud - I Love You, Bro. Always and Forever!/@comment-24364245-20170121172510/@comment-30458740-20170122162800

Only if they're claiming it to be theirs.

I spoke with the original artist who made this and others pictures, and he said that he's usually alright with anyone using his art, just as long as they acknowledge who originally made the art and they credit him. It's only claiming that it's theirs that he would consider it stealing.