Are teams allowed to revert to previous years components at will?

I was thinking about this today- using Toprak as an example, he was complaining about the new 2025 m1000rr chassis not turning, not braking the way he wanted...But he loved last years chassis.. So why not just use that?

Since the bike has been homologated every year it's been in production, can they simply choose to use last years parts? Or ones from 2,3 years ago?

Or are they stuck using the one based off the most current production model- this year being the new version '25 m100rr..?

In MotoGP, Ducati is basically using the same bike as last year, after both Marc and Pecco preferred the '24 to the updated 2025 spec.. But they are still in pre-season. I guess they locked it in before racing starts next weekend..

So I wonder if anyone knows what the rules are about using prior years components in WSBK? It seems like common sense- if you want to use "old" parts, then why not? It's technically a disadvantage.. Heck, the R1's have been fundamentally same for the last decade (with minor revisions, but no revolutionary changes)