Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32h5/STM32H503/I3C1/I3C_RDR#0x0
I3C receive data byte register
8-bit received data on I3C bus.
https://github.com/modm-io/cmsis-svd-stm32