Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wb/STM32WB10_CM4/HSEM/RLR21#0x0
Semaphore 21 read lock register
Semaphore ProcessID
Semaphore CoreID
lock indication
https://github.com/modm-io/cmsis-svd-stm32