OK, I understand the distinction "why QC is not sci-fi, just slice of life with sci-fi elements", but I strongly disagree with that assessment.
I don't think "how prominently does sci-fi feature?" is a good metric for whether something is sci-fi, or whether it is good sci-fi.
QC is sci-fi to me. Yes, it's true it's not JUST sci-fi, but it does explore situations that couldn't be explored quite the same way without the sci-fi elements. Those are often minor or played for laughs, but there's plenty of them. I don't think that's just for flavour, either. Roko's feelings about her new body are an example. Human-AI relationships are an example. Heck, the fact that AI use "QWERTY" as a swear word is an example. There are a *lot* of things that are very peculiar to the comic's setting, in my view.
If you can't *quite* write something the same way without at least some retooling, you enter sci-fi territory. I don't wanna kinkshame anyone, but I think a bread fetish is less common among humans than it would be among AI (and the story has gone into how AI perceive smell differently than humans on multiple occasions - from how AI buy stuff in coffee shops to Bubbles talking to Faye about how she shees the world).
I don't think sci-fi needs to be the exclusive, or even main, focus for a story to count as sci-fi. Don't many great sci-fi stories parallel real-life anxieties and questions anyway?
Yes, you could technically adapt the stories to a setting that doesn't include AIs and robots. But by that metric, Dresden Files is not actual fantasy because with a bit of tweaking, it could be rewritten as a straight noir story. Witcher is not actual fantasy because elves and dwarves are very clear stand-ins for real-life minorities in more than one way, and could be replaced with ethnic groups with no trouble.
Here's another way to look at this. Stanisław Lem is pretty much universally considered the greatest science fiction writer in Poland. And he wasn't shy about exploring issues of technology in-depth. But he also wrote "Dzienniki Gwiazdowe" ("Star Diaries", I think? Not sure what the English edition's title, if any, was), which is a series of absurdist short stories about obstructive bureaucrats and narrow-minded academics, framed through the misadventures of a space pilot. He wrote "Fairy Tales for Robots", which is exactly that. It's a bunch of fairy tales, but the knights and princesses are robots and also there's a metal dragon that lives on the moon. And engineers are basically wizards or scholars - not cool techno-wizards like in some stories, they functionally *are* wizards, with arcane knowledge and funny quirks and magical powers. All stories are framed using the typical fairy-tale conceits (a hero performing three tasks, a journey, saving a princess from a dragon). It could be argued that all those fairy tales could be written without robots with little trouble. That's... kind of the point of the stories. They are reframed as robot stories and that's part of the humour, the weirdness and "these are robots but they behave nothing like robots, but sometimes also they kinda do" IS the exploration of sci-fi themes.
I don't think I've ever heard "Fairy Tales for Robots" described as anything but science fiction. Same with "Dresden Files" and fantasy. In the same vein, I think QC is sci-fi slice-of-life. It's not just decoration, the sci-fi elements lead to unique characters and plot points that wouldn't *quite* be the same with a different coat of paint.
I don't think sci-fi needs to be hard sci-fi and be *all* about technology to count as legitimate, even in-depth sci-fi.
I understand the comparison to Star Wars, but I think SW is different in that it doesn't use the "spaceships and lasers" elements to explore plot points even in minor ways. The first movie *is* essentially a samurai story. I don't mind if someone calls it sci-fi (and thinking about it as compared to QC *has* made me reevaluate WHY I'm so adamant it's "space fantasy" and whether I'm just saying that because I've been conditioned to do so), even if I'm personally on the fence.
For QC, it's much clearer to me that I'm looking at sci-fi. I guess it depends on your personal definition. Then again, I don't think Firefly is "just western in spaaaaace" and Cowboy Bebop is "just a story about a former mob hitman, in spaaaaaace", even though they could be fairly called such.
YMMV.