power consumption +400uA with TFM enabled

[embeddedCoder]

I'm using the peripheral_lbs sample for testing with the PPK2 kit and the 1.0.0 nRF54L15-DK. 

I have disabled logging and serial and added PM_DEVICE and PM_DEVICE_RUNTIME.

A build for nRF54l15 DK nRF54l15 Application gives me low power I am expecting.

A build for  nRF54l15 DK nRF54l15 Application Non Secure increases current by a constant 400uA. This is visible by a constant horizontal line between peaks.

How can I reduce TFM power/make it sleep?

Thanks

[leap_lede]

Thank you Simon, this helped us resolve the same issue. 
Given we can't find more documentation about `CONFIG_MPSL_FORCE_RRAM_ON_ALL_THE_TIME`, do you have more information if this can be considered a stable fix to be used in production?