Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wb0/STM32WB09/TRNG/TRNG_DEFKEY0#0x0
TRNG_DEFKEY0 register
Bits 31 to 0 of AES 128-bit Default Key.
https://github.com/modm-io/cmsis-svd-stm32