Thank you for contacting Cypress Semiconductor.
I would like to inform you that all the sectors in S25FL128L device are 4KB sectors hence there is no concept of Low/High Parameter Sectors/Block in this device.
The 4KB sector erase time for S25FL128L is -
- Typical - 50ms.
- Maximum - 250ms.
Though we do not have a migration guide for FL-P to FL-L migration, we have one document that compare the features of FL-S to FL-L device. You can have a look. Link - https://www.cypress.com/file/334026/download
Please let me know if you have any further queries.