Alright, after reviewing old posts related to rollover nights, I now agree with DiverDave that my first post was actually correct. You can only earn rollover nights in a year when the nights actually stayed in that year exceed those needed to qualify at the status level that year; only those nights that exceed that status level requirement actually rollover. In a normal year a diamond with 61 nights in a year will rollover 1 night. In 2021, a diamond member must have at least 30 nights and nights in excess of 30 will rollover to 2022. While rollover nights applied to the next year will allow a person to prequalify for a status level, those rollover nights will not apply when calculating rollover nights for that year; to rollover nights the nights stayed in a year must always exceed the status qualification requirement for that year.

So after all this the formula I applied to the OPs scenario in my first post is correct. 54 nights rollover from 2020 to 2021. Based upon the lower status threshold for 2021, the OP has requalified for diamond. But rollover nights for the next year (2022) do not start to accumulate until the OPs nights stayed in 2021 exceed the diamond qualification amount, in this case 30. The OPs nights stayed in 2021 that exceed 30 will rollover to 2022.

54 nights rollover. 114 nights including the 54 rollover as of the OPs next night in 2021.
Applying the rollover from hilton.com:
114 nights
-54 rollover nights
-30 diamond qualification requirement for 2021
=30 nights rollover to 2022.

Sorry for all the confusion everyone.

See also these threads:
How does rollover work?
Roll over nights question
Roll Over Nights Question
Nights Rollover Multiple Years
https://www.flyertalk.com/forum/hilton-hilton-honors/1996187-hilton-rollover-night-credits.html