Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32l5/STM32L552/FLASH/ECCR#0x0
Flash ECC register
ECC fail address
BK_ECC
SYSF_ECC
ECC correction interrupt enable
ECCC2
ECCD2
ECC correction
ECC detection
https://github.com/modm-io/cmsis-svd-stm32