I'm not seeing what is obviously not practical about it?
Nope. I've watched it over and over, and I don't get it.
Now, to be clear, it *could* be very good cgi. But nothing in it is obvious cgi. And critically, nothing in the movement requires cgi.
If I were to speculate, I'd say perhaps you're assuming the water on the carapace is cgi? I mean, there's little else there to argue about. The rest is indistinguishable as real or not. The water on the carapace? I say it's real. There's also an odd effect, a sort of trick of the eye I think, that comes from the fast water moving down, and the slower drool (blood?) from the mouth, the different speeds might be what you think look fake?
But that looks like a practical alien to me. It's what they build those practical heads/working mouths & lips for.