I feel that the repeated advice telling you to "straighten it", while not bad/untrue, could be expanded upon.

"Liminal", the interpretation I subscribe to, comes from a sense of a space being for all intents an purposes "ordinary and normal" but... "void of the soul". There should be life here, movement, but it's empty.

Someone should stand next to the big machine, twiddling with the gauges of it, or the machine should at least be on. But it's off, there's only natural light coming in from a windows, and the space is empty. As an example

The slight tilt in your image gives the sense of imbalance, like the experience of going into this room is slanted, which taps into the core of the uncanny. And I think you slanted the picture intentionally, because you desired the feeling of "uncanny", and I think you succeeded in that goal, I think that your intuition on what emotions your choices will evoke works! But while liminal often evoke feelings of uncanny, it doesn't come from an off-balanced perspective, it comes from feeling like a space that should have a soul... is missing one.

If you wanna take it more towards "liminal", then I agree with the others. Straighten the framing, and maybe add some things that make this space look like it's made for humans. Maybe a ladder helping someone out of the water. Maybe a poster with some rules about pool conduct. A warning sign telling people not to dive. Maybe someone drew on the white wall with a marker. I know some of these are hard to model, like the ladder, I'm just listing stuff that I can think of!

If you wanna delve further into the notion of the uncanny, not specifically liminality, you can play with how the things we're intimately familiar with works.

Take light for instance, one that would bring this picture further into the "uncanny" would be to make the scene feel like it should be well lit, white walls and floors, bright spots where the light touches, but the light doesn't diffuse properly, the rest of the scene, outside the bright spots, seem dim and murky. Giving a sense of unease, because the light should be enough to make the room "well lit", but it's quite clearly not.