I only had the propulsion power reduced once and it was because I was going uphill with a depleted battery at 150km/h. This is normal according to the car manual, the lower buffer is depleted and we are stuck with the 86cv of the ICE.
I did get the Service High Voltage Charging System warning and the sensor and cabling were replaced under warranty and the updated was applied.
I tried the method from the video, didn't let the car running on idle until battery depleted, did try to leave it on with everything off but it takes forever to deplete the battery and eventually the car shuts down. So since I had good estimate about having at max 8.6 to 8.8kWh after the update I tried the mountain mode / normal switch a few times in the last three drives.
Today I went to a longer drive at higher speeds and usually at these speeds I would get lower kWh usage. I got 9.1 kWh, so it seems to work, but it's still lower than before the update.
What I have noticed after the software update is that my fuel usage is lower than before, probably more battery buffer available to use?