Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wl3/STM32WL33/I2C2/I2C_RXDR#0x0
I2C_RXDR register
Eight bit (8-bit) receive data Data byte received from the I2C bus.
https://github.com/modm-io/cmsis-svd-stm32