Impact of creating a public holiday on existing leaves

Hi experts,
We are wanting to know how it should work if the Public Holiday is created later, what impact does it have on existing leaves.

Example:
Employee has an existing leave on Jun 10 2025 (by now it is scheduled)
Then Public Holiday was configured today for Jun 10 2025.

How will it affect that existing absence scheduled? And what impact does it have to payroll?

Thanks in advance