Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Silicon Labs/EFR32BG22C222F352GN32/SMU_S/ESAURTYPES0#0x0
Write to specify if a region is secure or non-secure.
Region 3 Non-Secure Type
https://github.com/cmsis-svd/cmsis-svd-data