Masonry knee wall possibly load-bearing?

Hello,
in the house I have owned for about three years (built around 1970) I would like to make a small change in the attic. It concerns the following: In the large living room of the attic (which extends across the entire width of the house) the knee wall (is that the right term?) has been set inward so far that there is a huge unused area behind it. Presumably so that there is almost no sloping roof in this room.
I would like to install a 70 cm wide door in this side wall, which is about 160 cm high, so that the room behind can at least be used as storage. After a test drill, I found out that this wall is 16 cm thick and built with classic hollow blocks. Now I wonder if this wall might have a load-bearing role and if creating an opening for the door could cause me major problems.
Or whether one could say, regardless of whether it is load-bearing or not, a 70 cm opening wouldn’t cause any problems anyway...
The old building plans from the 60s do not contain a floor plan for the attic, only a side view which I am attaching. No idea if this says anything.
What is your opinion on this?
Best regards
N

A knee wall is the extension of the exterior wall up to the roof. I don't see that on your sketch; the roof structure lies directly on the last floor slab. What you mean is a dwarf wall. It partitions off a section so that there are no knee-high corners under the slope. Normally, these are not load-bearing and are drywall. In that respect, I'm also surprised that it is built of masonry. Basically, a breakthrough with a properly sized lintel should not be a problem. Do you have the structural calculation? A structural engineer should be able to tell you that for sure.

An indication against a load-bearing function could also be whether there is another wall under the respective knee wall (i.e., in the floor below). Because if not, the knee wall cannot have a load-bearing function, as it could not transfer the load downwards. However, it could be bracing, which is why it is always better to ask the structural engineer, although in this case I believe that a 70cm opening should be unproblematic...

Make a bigger hole (einige Mauersteine) where the door is supposed to go. Then you'll see what's going on behind it. Some photos are also helpful.

Thank you for your answers.
A structural calculation or other documents – apart from the construction drawings – do not exist. As mentioned, it is from the late 60s.
In the floors below, there is no wall at this point. That would also have created strangely narrow rooms on the exterior wall of the building ;)
I took a photo. The hole is already 70 cm wide. The height still needs to be measured.
What is interesting is that the wall consists of 12 cm thick pumice solid bricks.

Look into the hole with a phone camera and then look up. If the beams are not resting on this wall, nothing supports them