??? Separation? I don’t see it.
Exactly, that’s what I mean. Somehow a room divider, but not really decisive either.
Overall, this wall section is not clear to me: it is not apparent what it is supposed to visually divide or separate; it stands behind the sofa, but only on about half its width. It is an 11.5 cm wall, which is rarely used as a load-bearing wall. However, apparently a beam ends above it, which probably has something to do with a ceiling slab at the stair exit. I do not read any indications of more pressure-resistant stone qualities there in the plan, although opposite there is a concrete pad instead of a wall in the wall. This would argue against the assumption that this piece is purely decorative and could be omitted.
Visually, in my opinion, redundant, but structurally probably not dispensable (?) – the latter would also exclude choosing a half-height and/or lightweight construction.
If given the choice, I would provide a lightweight wall the width of the entire back of the sofa (but not install it yet), and leave a “gap” in the underfloor heating for it.
However, after closer examination of the drawing, I think: the choice does not exist, the wall section has a load-bearing function. Namely because of the beam, which has to be there exactly because of the corner missing from the 17.5 cm / 24 cm wall due to the slanted door.