Lemme just put my stamp of approval on here
Here’s pretty much how the design and illustration business works. After an artist has built a name for himself or herself, they’ll hire a bunch of freelancers or independent workers to take on a lot of the workload. So, if you hire Artist A for a project, you might just receive a job done by a struggling college student who make pennies off of every dollar you pay the artist you’re hiring.

Is it unethical? Probably, but as long as the artist gives a stamp of approval and the client likes it, why does it matter? Everyone’s happy with the work, and a starving kid looking to make a few bucks on the side gets to eat something other than Ramen for once.