I wouldn’t have pegged it as an Oscar winner at all; more of a niche movie, but I guess the Oscars are trying to widen their appeal, and this kind of weirdness maybe has more mass appeal post the Marvel movies’ forays into time travel and multiverse stuff.
The truth is there have been a lot of Oscar Best Picture winners that are nothing special when you watch them again. This one was more interesting and memorable than half a dozen other winners I could name.