I guess the black credits fixed it, it stood without being taken off for quite a while now.

Thank you all for the help, I appreciate your time.

Next time I will make sure to be using more visible and more exact credits!

And (just saying this as an opinion) the message for the non proper credits would be very useful in terms of feedback for the person who gets the art banned. Like if I had gotten a mail "credits not visible" or "credits too small" or "credited the wrong person" this whole mess would have been easily avoided and the credits would have gotten fixed right away.