Interior construction is faulty or executed in poor quality

That is correct, but who is supposed to judge this from here, especially without pictures. So one can claim a lot. Therefore, I wanted to put this into perspective a bit, that it does not necessarily have to be a defect.

Presumably, both during construction and before the warranty expired, savings were made on the expert, otherwise a solution could have been found at the latest two years ago. Now complaining about defects whose onset started shortly after completion, I find somewhat late.

Of course, we immediately documented everything visible, also in writing. The issue with the [Rollläden] came later, it can happen that a [Rollladen] is sometimes defective, but in the meantime we had 8 or more defects. Of course, repairs were always made, but somehow this really goes too far.

Of course we documented everything visible immediately, also in writing. The issue with the roller shutters came later, it can happen that a roller shutter is defective, but in the meantime we had 8 or more defects. Of course, repairs were always made, but somehow this really goes too far.

What roller shutters?
In the initial post and in your second one, roller shutters were not mentioned... in the next post it's about the toilet flush that is defective? Which was repaired? And you need advice?

You can't be helped like this if you just claim something without fundamental evidence.

Within 5 years you have warranty claims according to the Building Code. You do not repair yourself, but report a defect to the construction company.
They are then obliged [to fix it].
After 7 years, of course, no longer.

Edit: if expansion joints or silicone seals are not included in the construction specification, then this is the responsibility of the builder, i.e. to be done by the client.
Not uncommon with timber frame construction.

Regards

Huh, what kind of toilet flush? That must be a mix-up

The entire thread contains neither even a vague problem description nor a real question. How is one supposed to help like that?

The entire thread contains neither even a vague description of the problem nor a real question. How is anyone supposed to help like that?

The question is right there in big letters: "Who has such problems in their prefabricated house...?"
Is it allowed to write here with whom you built, that might perhaps appeal to builders who built with the same company.
Otherwise, tearing silicone joints or cracks at the connection points are certainly not unusual, bending door frames, to whatever extent, more so.
Are these electric shutters or what exactly is breaking on them?