first off: You are the single person who has responded to this post admitting some variant of having done this that actually listened to what was being said, acknowledged that you did such things while you didn't know any better, expressed an intent to never do it again, and asked for clarification on whether or not "creepy deer aesthetic" is completely off-limits with that in mind. So with that said, I want you to know that you're one of the very few folks in this post I respect sincerely.
To that end: While obviously I can't speak for Native America as a monolith, it would be my opinion that no, creepy deer aesthetics as a concept are fine. Deer can be fucked up and weird. There is a fundamental lure to the idea of a large prey animal behaving as a predator or in ways anathema to our understanding of prey. That juxtaposition and irony has a lot of narrative potential and for good reason--it fucks severely! I don't want to see it go away! It fucks hard, for Christ's sake!
But it is my opinion that the use of deer aesthetics within the specific context of cannibal themes isn't able to be used anymore. The well has been poisoned too deeply. I never said once the specific being I was referring to in nearly any of my responses, but everyone knew exactly what I meant. Even trying to purposefully distance the racism from the imagery would be useless, since the racism is baked in to the assumptions by now. Reclamation may be able to happen in the future, but first we need to accept that setting it down completely is the right play for a while. You can distance racism from creepy deer stuff by purposefully and actively distancing it from Native America and cannibalism--if it becomes a recurring imagery on its own throughout multiple types of horror, rather than being innately tied by implication to the winter hunger, that's when we could maybe begin talking about whether or not to start re-examining our relationship with it.
EDIT: I forgot to add this but I will say my only criticism of your response is your use of myth/fiction to refer to supernatural beings. No one is saying that a gorgon or pegasus isn't a mythological creature--but the Greco-Roman empire has been long since dead. Additionally, Greek monsters were a coinflip on "we acknowledge and believe this to be invented contemporarily, such as Scylla and Charybdis or the crashing cliffs" and "we genuinely believe that this monster is real bc thats how religio-spiritual beliefs work". But the Greco-Roman empire is long-dead. There is no state-organized practice of Hellenic or Homeric or any sort of Greek paganism, it's all neopaganism or individual atemporal reconstructions. The hydra is allowed to remain a myth because no one is hurt by doing so.
But referring to indigenous supernatural beliefs/history as mythology is deeply, fundamentally, and extremely racist. Defining nonwhite cultures' beliefs as Myths or Legends is an inherent tool of white supremacy and Christian imperialism. Jesus is not considered a myth. Joan of Arc is not considered a myth. Look at what cultures have their indigenous practices, religions, and histories get labelled as "myth" and you'll see where Christianity has rooted itself in oppressing those cultures and communities, silencing and smothering them. Nobody is hurt by the hydra being a myth, because the culture of the Greeks who it would have hurt has been dead for centuries.
But what about Native Americans? We're still here. We're still alive. We're still holding firm to our beliefs, our histories, our spirituality, our religion. Calling the shit that y'all have stolen myth is intensely racist. It discredits our agency, our intelligence, and our cultures, and it helps distance Native America from modernity. It frames us as ancient and dead as the Greeks. It disrespects the possibility of our cultures as refusing to bow down or give in or cede ground, disrespects our religions, and all so much more.
Stop calling indigenous folklore and beliefs as "myths". Stop treating them as monsters for your Dungeons and Dragons campaign. Stop acting like this is a huge and unreasonable demand that we not be insulted to our faces even further with y'all's thefts.