I may follow some of these up. I read loads of sci fi when I was a kid, classic space opera thru all Asimov, Clark, Heinlein etc to Ballard, but none in the past 20-30 years apart from Iain M Banks which I love and reread.
Anyway, another vote for the Iain Banks’ ‘mainstream’ literature, much of which is pretty close to sci fi/fantasy (Walking on Glass, the Bridge, Transitions.)
(I vaguely recall reading him saying it was pretty random the way his middle initial made it into his sci fi name, and that it was never deliberate to differentiate.)
Another suggestion, not genre sci fi though it wanders the edge with fantasy and pushes a lot of the same buttons, is David Mitchell, who’s quite happy to go off into dystopian futures etc with, with a feeling that anything is possible…
Finally, if you’ve not read early (or middle or late come to that) Kurt Vonnegut, lots of that is sci fi, kinda (sirens of titan).
I guess I must like my sci fi in a literary plain brown paper wrapper…