The employee originally had a higher paying position for 2 years, then willing switched to another job within the same company for less pay.
To my knowledge there is no contract of how much the 2nd, less paying, wage is or should be. HR has documentation of the job posting, but I am not aware if any salary or wage details were sighted in the job posting.
HR has informed the employee that 'many managers have since left' from the time the job switch was made and that this is a 'extremely odd' scenario. Take that FWIW.
The hospital wants to reduce the employee's current wage by 30%.