Kodiaq iV PHEV battery capacity vs Charge level?

Hi all, a question:

We enjoy having a 2025 Skoda Kodiaq iV PHEV.

In last year's software update, you can now choose (and it is recommended) to have the maximum charge level automatically reset to 80% after a charge.

We only charge to 100% occasionally if we know we have to travel further the next day, and then the car automatically resets it to 80% for the next charge so that it never stays at 100% for long, as that would be bad.

Our specific question regarding our Kodiaq (and therefore also regarding the VW Tiguan or Cupra Terramar) is the following:

Skoda states that the battery has a capacity of 25.7 kWh, of which 19.7 kWh is usable.

So if the difference between 0% and 100% is 19.7kWh, is there an extra safeguard built in by, for example, keeping 3kWh at the bottom and top as a margin to prevent deep discharging and maximum full charging, thereby extending the battery's lifespan?

So 3kWh at the bottom, then the 19.7kWh usable (0-100%), and then another 3kWh at the top makes that 25.7kWh??

3kWh + 19.7kWh + 3kWh = 25.7kWh?

Incidentally, that would mean the 80% setting would indeed remain well below the "true" 80% of the full 25.7kWh. 25.7 - 3 at the top is 22.7, which would be the 100% you see in the car, and 80% of that is approximately 18.16 kWh.

That, in turn, would be 70.6% of the actual 100% (25.7 kWh), which aligns well with what experts say about extending battery life.

You read more and more that 70% is even better than 80%?

I am curious if anyone has factual information on this and what your view is on it.

Thanks for your responses,

Leo