Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32l5/STM32L552/FLASH/SECHDPCR#0x0
FLASH secure HDP control register
HDP1_ACCDIS
HDP2_ACCDIS
https://github.com/modm-io/cmsis-svd-stm32