If you ask AI this in different ways you get opposing answers: sometimes it says it makes ride harsher, other times more comfortable. That's AI for you

I have made the change twice. Both to OZ (leggera and ultraleggera). Once on a 997, with the same tyres switched over, and the ride was better.
And on my Clubsport S and the ride is leagues better BUT on this one I went from 19 prets to 18 OZs saving 2kg a corner, and had new tyres so those two probably explain much of the improvement.
Have you changed the tyres too? There is a lot of sidewall stiffness variation between makes - even with same load rating.