Personally, I feel it’s actually the other way around.
macOS is mature and familiar. Sure it gets a new splash of paint every couple years but since at least Mavericks, when updates started to become free and yearly, it’s just been changing very little, but steadily adding nice things to have.
iPad OS it’s truly the one having an identity crisis. It’s multitasking interface seems to get redesigned every year, and every year it seems to not be able to keep up with either of its older brothers.
It’s still far far away from a Mac, but also, you can’t even call it “iOS on steroids” anymore because it’s not, it still doesn’t have several of the features introduced in recent versions of iOS.
It doesn’t have the new lock screen, it doesn’t have any battery management, it doesn’t have certain camera features, it can’t even be used as a home hub anymore, it doesn’t have a proper Wallet app, it doesn’t have Apple Watch compatibility… it doesn’t know what it wants to be.