Plaster on the underside of the reinforced concrete staircase shows bubbles

Hello,
we moved into our new house at the end of 2015, which we planned and realized with the developer Fell Das Haus.
After various issues and their resolution, we are reasonably satisfied, but a few months after moving in
we noticed that bubbles had formed on the underside of the reinforced concrete staircase. The executing company was the painting company Hofmann from the area.
After the complaint and several changes of site managers at company Fell, there was an expert report commissioned by the company itself in 2017, which confirmed the defect. Unfortunately, the expert, Mr. Baureis, does not provide me with the report since it was commissioned by the construction company. After numerous reminders and deadline settings for defect correction, I unfortunately received no further response from company Fell. But that is just the introduction (and this is not meant as an evaluation of company Fell!) and by now it hardly matters, my question to people or forum members who may have experienced similar issues with interior plaster is:

Can these bubbles damage the plaster at a later point in time? Or is it just a cosmetic defect?

We are of course somewhat disappointed by the reaction of company Fell Das Haus, but it would be more important to know whether such bubbles are indeed a construction defect or not? If necessary, we will have to have it repaired ourselves.

Thank you for the feedback.

Hi,

There is no technical defect. The bubbles are caused by air pockets between the two layers of plaster and appear on the outside. When troweling, they are evened out and are no longer visible after floating. The occurrence of bubbles is a sign that it was troweled or floated too early.

Depending on the quality you have agreed upon, it is still a defect.

Hello,
the developer has meanwhile commissioned a master painter to eliminate the visual defect.
After the correction, we are now satisfied. The bubbles are no longer visible.

Thank you very much for the feedback and the explanation.