Thanks for posting that postsaurischian. I googled green ara and I can totally see the resemblance in the color scheme of their Anzu, assuming it was based on this bird:
https://en.wikipedia.org/wiki/Great_green_macaw Regardless if the sculptor of the Anzu copied the color scheme of that artwork, the original color scheme was derived from nature. I suppose this would be like if I used the colors of a Dwarf Gourami on some dinosaur, or other prehistoric creature and someone went and did the same for a figure. I suppose at this point it was just merely copying someone's idea, since the color scheme itself was derived from nature, and not a completely original design. I'm not sure where the lines are to be drawn in a case like this.
Honestly, it would be nice if no one copied anyone else in this market, but that's not how it is these days, and that's not even counting bootlegs. Of course there's various degrees of it. You have either nearly complete copies of someone's artwork (in the case of the Schleich 2018 Carnotaurus with the color scheme, and scale and scute shapes, or the Safari Ltd Oviraptor with nest, with colors and pose, etc), or just the color schemes copied, but used on a different species (in the case of the Papo Cryolophosaurus using the Sideshow Ceratosaurus color scheme). There's also all the JP (and Sideshow) knockoffs out there from Papo, other companies, but that's one company using another company's design, versus a company using an individual's design.
As someone who creates things, I'm not sure I'd want my ideas or designs used and then sold without credit, or perhaps without even asking permission, in the least, so I can't say I look favorably on this practice, but ultimately it is also up to the original artists to go out of their way to protect their works (although they also can't do anything if they don't know about it). Of course there's also those that are completely fine with it. So for me this is a hard line to draw, and it would probably have to be a case by case basis.