The process of erasing flash is delayed in SDK15.3

[Sawada]

It takes time for fs_event_handler to be called back after nrf_fstorage_erase is executed.
In SDK13.1.0, it didn't take much time, but in SDK15.3.0 takes time to be called back.

SDK15.3: nrf_fstorage_erase()
-> 4 second
SDK13.1: fs_erase()
->0.2 second
*Each erase function is called directly from main() .
*The erase function called in SDK15.3 is in "nrf_fstorage_sd.c".

[Sawada]

It was described in the following thread.
sorry.

https://devzone.nordicsemi.com/f/nordic-q-a/26929/sd_flash_page_erase-on-nrf52840-takes-a-long-time