Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32h7/STM32H723/FDCAN1/FDCAN_TSCC#0x0
FDCAN Timestamp Counter Configuration Register
Timestamp Select
Timestamp Counter Prescaler
https://github.com/modm-io/cmsis-svd-stm32