What kind of dormer is this?

Thank you very much for the idea and representation of feasibility. A dormer gable would then also be possible with a gable like in my photo?

I wanted to address the dormer with the construction company, but apparently, it is not that easy to implement because of the knee wall. We initially expected a roof pitch of about 45 degrees, and then the dormer would supposedly be at a height of 1.20m - not perfect for a children's room.

Can someone tell me what the reason for this is??

Why don't you do the dwarf gable like in post9? Although I don't quite understand what you mean either.

Can someone tell me what this is caused by??

you should ask your contractor about that. He can explain exactly what is feasible or not, and why, based on a cross-section

Regards