Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wl3/STM32WL33/FLASH_CTRL/UNLOCK3#0x0
UNLOCK3 register
(NOT TO BE DOCUMENTED) Remove read-write protection from IFR3 sector
https://github.com/modm-io/cmsis-svd-stm32