Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wb/STM32WB55_CM0P/SYSCFG_VREFBUF/VREFBUF_CCR#0x0
calibration control register
Trimming code
https://github.com/modm-io/cmsis-svd-stm32