Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32h5/STM32H503/SBS/SBS_HDPLSR#0x0
SBS temporal isolation status register
temporal isolation level This bitfield returns the current temporal isolation level.
81 (B_0x51): HDPL1, iRoT
111 (B_0x6F): HDPL3, application
138 (B_0x8A): HDPL2, uRoT
180 (B_0xB4): HDPL0, RSS
https://github.com/modm-io/cmsis-svd-stm32