I take the stance that you can't claim one group's mythology is off limits but it's open season on another's. If people are allowed to write stories like Good Omens, Marvel's Thor, and Percy Jackson and the Olympians despite not believing in the religions that spawned them, then the rules should be equally accepting of something like Skinwalkers.
I kinda take the stance that the more you show your work, the more you have earned the right to use the creature. Either by going hard and building your own version that is entirely unique like a certain puppet said, or integrating the IRL culture’s beliefs into it. This goes double if there is another entity from your own culture that would have worked roughly as well.
Jim Butcher in the Dresden Files, for example, does angels pretty much perfectly from the POV of me, a Christian. The main angel character we see is a behind the scenes chess master who seems to be completely, earnestly benevolent. He manipulates events books in advance to make sure that all things work together for good. Everything looks like a coincidence. He’s just straight up not allowed to interfere with free will or its fruits directly, and whenever he is given any leeway he makes the most of it. He FEELS like how angels are implicitly assumed to behave by most Christian’s I know. That makes it extra good and I feel very seen.
From what I’ve heard, his use of skinwalkers is also considered generally good because hot damn Shagnasty (Dresden’s nickname) is truly horrifying and very very evil. I imagine there are people who hate his inclusion as an antagonist, but I’ve never seen evidence of their existence and I’m 90% sure at least half of them are non-native busybodies if they do exist.
For contrast, JK Rowling’s canon for Skin walkers is that muggle medicine men spread malicious rumors about native wizards, painting them as horrible monsters that should be exiled at the least and preferably killed on sight. Thus declaring that the Wizarding World cultural and religious leaders were a bunch of charlatans with very few exceptions. Which… Yeesh. Unironically worse than just not explaining anything imo.
WITH THAT SAID, I’m not a web fiction cop and I don’t consider even lazy cultural appropriation to be a big deal. I just feel like it can be done better or worse.