Science fiction horror is hard to pull off. Most movies that claim to be sci-fi horror are really just one or the other.
The horror genre works by grounding the reader in a world that is good and whole and then introducing some wrongness or threat that undermines the assumptions of that world. The horrifying thing at the center of a horror movie needs to refute or destroy or at least challenge the world that encounters it.
Science fiction works by establishing a world where the rules are different from the rules we know. That means if you’re going to make a science-fiction horror movie, you have to teach the viewers a whole set of rules and then violate those rules, all in the same work. Mostly, though, movies that claim to be “Science-Fiction Horror” are either a horror movie where the horror happens to be from space (like The Thing) or a science-fiction movie where the rules of the world are scary (like Terminator).
The only real Science-Fiction horror movie I can think of is Alien, and to be honest I don’t really understand why it works so well: It’s just magic.