A lot of the royalty free images I have bought prohibit using the imagery as part of the logo for a company.
But maybe the platform where the bird graphic was sold did not say any such thing in the licensing terms. In which case, tough luck to the artist.
And on the other hand, if there were such terms agains using the graphic as your logo then the artist should have sued and gotten a sizeable payment.
This is right, and the second half is what bites. Standard stock licenses generally prohibit use in a trademark or logo outright, and the extended license that permits it still gives you no exclusivity, so the image stays on sale to everyone else.
That is why logo marks get commissioned with an assignment of rights instead of bought off a stock site. You are not paying for the drawing. You are paying for nobody else being able to use it. A company that grew into a global brand on a non-exclusive stock bird got lucky that nobody claimed it first.