ᐅ Loud Staircase Noise from Neighbor’s House – Is the Staircase Properly Decoupled?

Hello dear forum community,

I have a question:

We have been living in our new house (semi-detached) for a few weeks now.

When our neighbor walks up or down the stairs, you can hear it quite clearly in our half. The same happens the other way around.

According to the builder, everything is (as always) "fine" – which we strongly doubt given our shared history.

Now, the stair construction is supposed to be decoupled from the wall by a plastic sleeve (see photos). However, it seems to me that this sleeve just rests around the suspension and the metal is still in contact with metal (so no actual decoupling has been done).

Does anyone have experience with stair constructions like this? How can you check if it’s done correctly or if what we have is right?

Thank you very much for your answers!