Salary change when switching roles after PCS

For corporate folks - any idea what happens to your pay if you switch roles right after PCS?

I understand that future PCS exercises (i.e. from 2027) will obviously be done based on the new role, but what does it mean for this year's PCS? Does it get "voided"?

For example, if your new role is at the same level but has a lower pay band, does your salary get adjusted down immediately?

I figure Amazon can't just rescind stock grants, which means one's pay up until April of 2028 is largely fixed at this point - but that seems a bit too good to be true and I'm curious if anyone knows better.