Concrete stone glued with construction foam

Hello dear community, we are building with Town & Country and something caught our attention during the last visit to the construction site. The building blocks in some rooms were glued with construction foam, is that how it’s usually done? There were always two stones per room,

Presumably, the stone was installed afterward. Using foam is much easier to secure it firmly than using mortar.

If plaster is applied afterward, no one will see it anymore.
Using construction foam is common.

The question is rather why it was installed later, what was the reason?

Best regards, Patrick

Was the wall built up to the ceiling? That would at least explain why the last stone was then pushed in like that.

Some areas were initially not bricked up with stones because the Docastützen for supporting the filigree ceiling ran there. According to our site manager, they are embedded with fabric during the plastering work.