Answer
While a pay is still a draft, the web app may refresh leave rates and valuations as earnings, dates, work pattern, ordinary hours, or historic pay data change. This is normal because annual holidays and some other leave payments depend on the pay context.
Once the pay is completed, the leave quantity, rate, valuation details, and conversion basis should be treated as the banked payroll record for that pay. Later changes to the employee's ordinary hours, work pattern, or pay history should not silently revalue that completed leave row.
If a completed pay was wrong, correct it deliberately: reopen/edit only if that is your normal correction process, or enter a correction pay and a manual leave adjustment. Keep notes explaining the original setting and the correction.
