Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/STMicroelectronics/STM32H7x5_CM7/RCC/D1CFGR#0x0
RCC Domain 1 Clock Configuration Register
D1 domain AHB prescaler
D1 domain APB3 prescaler
D1 domain Core prescaler
https://github.com/cmsis-svd/cmsis-svd-data