Floor plan single-family house gable roof 1 full story 140 sqm

No, it has a gable roof but with a slightly elevated knee wall. The 2m line is at least indicated in one of the floor plans.

I would like to edit this above but unfortunately that is no longer possible.
Therefore, I am attaching here again the location of the plot in a north/south orientation as well as a cross-section for better understanding.

If the ceiling height is 2.30 meters on more than 2/3 of the upper floor, it should be considered a full floor in Sachsen-Anhalt. That should be the case for you.

Can you please upload a site plan and mark the plan with a north arrow?

About the floor plan
I find the house too small for a straight staircase.
Especially on the upper floor, the hallway is large compared to the children's room and office.

Draw your existing or desired furniture to scale.

Ground floor

Large entrance hall, nice coat rack missing.
The kitchen could offer more storage space without the peninsula (which is quite small) and without the dining area that is 3 steps away from the dining table.

Utility room quite small. You have all the house connections, building services and utility room accommodated here. Storage for dirty laundry, beverage crates and sports bag is missing.

Do you really want to block a sliding door with the sofa?

Is it correct that you are planning without a fireplace?

Upper floor
The parents' sleeping area is as large as the hallway and child’s room combined.
The child sleeps, plays, learns and meets friends in their room.

The bathroom is poorly planned.
Door opens and you run into the shower. The sinks that are frequently used are hidden.

If the ceiling height is 2.30 meters on more than 2/3 of the upper floor, it should be considered a full storey in Saxony-Anhalt. That should be the case with you.

Magdeburg/Schwerin is Mecklenburg-Western Pomerania, but they have the same regulation. I see it that way too.

If more than 2/3 of the upper floor has a ceiling height of 2.30 meters, it should be considered a full floor in Saxony-Anhalt. That should be the case for you.

The planner said that would pass. They are not so confrontational here and minor changes are also approved. We have already been to the responsible authority and got it approved.

Regarding the floor plan:

I completely miss the west orientation here: if you build the house at the height of the left neighbor, you have the west side free from "giant blocks." I would install proper windows there to let the west sun in.

open kitchen, kitchen island = open

Missing. One kitchen is too small for an island, the other does not have dream dimensions for an island kitchen.

There is still a lack of a proper wardrobe where you can store all the jackets and shoes of the seasons.

Basically, the floor plan is a very common one, often built. Typical, without a wardrobe closet, small children's room, large bedroom.
The bathroom is okay but I would furnish it differently.
I also see the problem with the straight staircase here. Building over it is not wise, as it will be quite steep. One step is missing.
A storage room would be good for the upper floor.
I would probably build somewhat longer (and narrower) and have the entrance on the side. Living, dining, and kitchen in a row on the west side. But it doesn't have to be.

Is there a building window?