Rust spots on concrete - ceiling to wall - new construction

What if it is actually reinforcement that is not sufficiently covered at these points?

I have already answered that:
The spot(s) must be opened (this takes 3 minutes per inspection point), checked, if necessary remove the foreign object and plaster again.
If it really concerns reinforcing steel, then proper repair is the task of the general contractor. Laypersons should keep their hands off (see among others ZTV-ING or DAfStb - Repair of concrete structures).
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Regards: KlaRa

Thank you very much for the answers!

Attached is another photo of the rust spot, where you can see the rust and moisture around the spot more clearly. The other smaller rust spots are all on the walls (not on the ceiling) about 3 to 4 cm away from the ceiling, distributed throughout the entire room.

Is there a possibility to check in 3 weeks at the handover whether the defects have really been properly fixed? Would it be useful to bring someone (expert, construction technician?) or since you can't see through the walls?

If it really is due to construction steel that is not sufficiently covered, after a few years the rust will become visible again or we will be in danger without knowing it (rust spots hidden by wallpaper/paint?)

Questions, questions...

The first picture (my first post) is not from the worst spot. Please look at the picture I just posted. Thank you very much..

Hello Nemnem

what is stopping you from getting to the bottom of the problem? The cause of the rust can't be too deep. So, open it up and take a look.

Steven

We are not allowed to enter the house; unfortunately, there is no possibility to come in again between the acceptance and handover date.

I suspect that these could also be cigarette butts...