I just noticed by a power measurement that the TX power from the RAK4631 on 2.0.12. is 0 dBm (or even less) INDEED! So maybe that remote parameter request result has been correct?
Just for confirmation i erased the flash again and re-installed 2.0.12 and applied the settings.yaml. Still, 0 dBm!
Then i took a different hardware RAK4631. Same result!
I read something about a power issue in the new release 2.0.13. Will check that now…
Confirmed! 20 dBm = 20 dBm, from now on!