The engines are not exactly the same. The '19 up is direct injected, and has a little more power.How is it the 2022 Wilderness has a 3,000 tow capacity when it has the
same engine etc as the 2017 Forester. What does it have that the 2017 doesn't.
Although the 12 extra hp is not really that noticeable. It may be in the CVT programming, ot throttle programming. My wife's '17's throttle is much more touchy than my '21.
It might show up on a wheel dyno, but not so much on the butt dyno.
Like zachavm said, the oil cooler probably helps, and I'm sure the differential gearing helps a bit too, as it takes some of the load off the CVT/engine. Not sure what they did with the brakes, if anything, as that also plays into the tow rating.
Without looking into it, it might be 3000 pounds with trailer brakes, and less without.