ok right, indeed it's interior, and has happend already at different
walls, various positions on wall, including on totaly indoor wall (no
exterior side). No water infiltration
I can rule this out for sure. Always only on load bearing concrete
wall. The exterior is brick so no problem apparently there. The
problem appered on ground level and 1st floor.

The plaster it's usual gypsum, about 6/16" thick, for interior,
smooth mat finish. I used it already to successfully repair a few
holes.

as for the options I proposed as remedy,

-the prefab plaster is the gypsum blue boards, on a metalic base
safely attached on existing walls, without removing the existing
plater.

- total replastering plus concrete treatment ( most expensive? )

- some durable glass fiber wallpaper (not the most aesthetic for
sure)

or wait and repair/repaint as the problem appears, this is the cheapest
but most taxing solution on our nerves. 1 wall per semester...if lucky