The new leave request allows an employee to select Fallback Leave Type even though the field has been populated with the leave type associated with the requested leave.

An employee can also change this with other paid leave types linked to them including the leave type they are trying to request for. I.e. Employee applied for Annual Leave and did not have enough balance; fallback leave is defaulted to unpaid leave. The employee then changed this to Annual Leave. So, the leave type requested is Annual Leave and the fallback leave is also Annual Leave. Employee able to submit this leave and the manager approved without noticing the Fallback leave is not correct. In the end Payroll has to fix this because the balance has gone into negative.

If the Leave rules is set for employee who does not have enough leave balance to go to Unpaid Leave, then why the employee is allowed to change this Fallback type to other leave types, even for the same leave type.

They should be prevented to change this or add a setting so that the business can decide whether to allow Fallback Type leave to be amended or not.