@tangible1 In principle I 100% agree, but it's quite possible the (rear) spring rates haven't changed at all. Personally I never felt Tesla's chosen spring rates for the Y (or 3) were anything extreme, they not the cause of comfort issues, though yes it's certainly possible Tesla went softer for the new suspension.
Rear springs are the quickest, easiest part to swap though (among the pieces involved here). If at some point it's shown the rear spring rates changed, it should be quick and easy to swap them later, no big deal.
(Well, I'm basing that on the Model 3, I believe everything fits together pretty much the same on a Y though.)