Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wl3/STM32WL33/MR_SUBG/AFC1_CONFIG#0x0
AFC1_CONFIG register
Length of the AFC fast period (in number of samples unit)
https://github.com/modm-io/cmsis-svd-stm32