Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32u5/STM32U545/OTFDEC1/R3NONCER0#0x0
OTFDEC region x nonce register 0
REG3_NONCE
https://github.com/modm-io/cmsis-svd-stm32