What is "Cut2.1" vs. "Cut2.0" and how can you tell what you've got?
RE: STM32Cube_FW_WB_V1.7.0\Projects\P-NUCLEO-WB55.Nucleo\Applications\BLE\BLE_HeartRateFreeRTOS\Core\Src\stm32_lpm_if.c
/**
* The switch on HSI before entering Stop Mode is required on Cut2.0
* It is useless from Cut2.1
*/
Switch_On_HSI( );
Seems like it would be great for efficiency if we could deterministically avoid this work in and out of power off mode.