ᐅ Horizontal crack in the wall

Hello,

I am new here and hope this is the right forum.
We visited a house that I am very interested in buying. It is a prefabricated house, Elk Magic 159, about 12 years old.
At the stairway landing between the ground floor and the basement, there is a horizontal crack on the wall (not an exterior wall). It’s not very large, but it is visible. The agent calls this a settlement crack.
Question: Is this a sign of serious subsidence, or can cracks like this happen sometimes?
The owner offers to repair it before the sale. He is a builder himself and has the craftsmen to do the work. I made a counteroffer that we would do the repairs ourselves (there are many craftsmen in the family) if the price could be adjusted accordingly.
I appreciate any opinions,
Tobi

You would need to check exactly at what height this crack is located. Maybe too little adhesive was applied right there. The same happened to us. We embedded mesh and hope that this will be enough.

Here, several high-resolution photos with plenty of light would certainly be appropriate.