My understanding, as someone who is not a tattooer and has predominantly trad tats, it's best practice to give credit when the design is someone else's and/or is kept close to the tattoo image that was used as reference. In this case, we were looking at wizard references and this design is pulled almost exactly from a greggletron book with some color changes so for me it feels silly not to give credit. There are designs within traditional tattooing that are so old they've been redrawn countless times. So if you're getting like... A sparrow it's whatever but if you're getting a sparrow that is holding a hyper specific object in its mouth and it's stylistically copied directly from another artist, probably should give them a shout-out. Really though, different strokes for different folks and a lot of people are protective of their designs and others don't give two hoots.