Vapor barrier for gable roof

Hello!
Old house built around 1900! Normal pitched roof house. I believe it's called a gable roof.
The exterior wall consists of a layer of regular red clinker bricks. At least upstairs in the attic.
That's what my question is about.

It's about the attic apartment. The floor is not fully developed, up to the gable roof.
Two rooms are finished there. With plasterboard panels. Timber framing. The conversion took place in the 70s.
One plasterboard wall that I want to redo now is about 30 centimeters away from the aforementioned red brick clinker wall, which is also the exterior wall. So the normal exterior wall of the house. I want to renew this plasterboard wall and move it closer to the exterior wall, and then insulate with mineral wool in between.

Now the question! Do I have to insert a vapor barrier foil between the red brick clinker wall and the mineral wool?

So this would be the order if I were to insert the vapor barrier foil.
Exterior clinker wall (10 cm red brick) / vapor barrier foil / mineral wool / OSB board / plasterboard wall.

Does a vapor barrier foil even have to go in there??? The exterior wall could release moisture into the mineral wool, that's my concern? But mineral wool is already there in the unfinished (cold) attic.

How should this be viewed?

The OSB board that I want to install under the plasterboard acts as a vapor barrier on the inside, so in that sense, I wouldn’t need a vapor barrier on the inside anyway.

It’s not about doing it 100% according to the norm, but minimal and sensible!
Because it’s an old house anyway. But I don’t want to have mold.
But I don’t fully understand the whole thing with the vapor barrier!

The vapor barrier always goes on the warm side, so on the inside. It is supposed to prevent moist air from penetrating into the colder layers and condensing there. If you have a wall construction where moisture can dry out (ventilated facade, for example), you probably don't need this vapor barrier, likewise if you have an airtight wall construction on the inside; supposedly tightly laid chipboard panels are considered vapor-tight. On the outside, no vapor barrier is needed; the exterior wall should be impact rainproof and accordingly no moisture from outside should be able to penetrate the insulation. Regarding the gypsum plasterboards: I don't really think much of them, especially in an old house or wooden construction (roof truss), since they are combustible. Much better to use gypsum fiber boards, which are non-combustible. But that is just my personal opinion.