@drakonic you mean like someone selling a commission piece of like idk niko oneshot without being nightmargin themself? or something like selling oneshot buttons without being nightmargin? (though ? isnt that stuff literally fair use, at least according to US copyright law? if i make art using my own skill but characters of someone else, while not making a market substitute, im pretty sure it is fair use. itd be different if i made a clone of the videogame for example. though i also heard disney could sue you for selling mickey mouse art)
though i guess it is a case by case thing here.
if i was a small business artist and sold merch of my characters and someone else was undercutting me on product i sell using the art i made (like as in literally ripping the png and putting it on merch), i'd first just discourage my followers from buying, but if that wouldnt work and i suffered damages i might actually sue. (this scenario is what i was referring to with the material goods require ip.)