The building authority rejects the building application because the house is planned too far back

Yes, the planner was dismissed.

Once again for understanding:

The actual planner who also worked on the premises of the construction company unfortunately died in a fatal accident at the end of last year.
After that, the construction company had to find a new one so that everything could run somewhat smoothly. They had no prior experience with this new planner.
Many customers complained about her manner and incompetence. The comparison to the former planner was like day and night.

Since the construction company does not want to drive away its customers and also wants to maintain a certain standard, she was now replaced.
So a completely normal reaction, right? The number of complaints was decisive and not just the problems I had.
Other customers also experienced mistakes in the building application. Heights and calculations were partly wrong. Her response to the notice from the building authority was that the clerk was probably being picky and should not be so strict.
Greetings of professionalism

Yes, the planner was dismissed.

To clarify again:

The original planner who also worked on the premises of the construction company unfortunately died in an accident at the end of last year.
After that, the construction company had to find a new one so that everything could continue somewhat. They had no prior experience with her.
Many customers complained about her manner and incompetence. The comparison to the former planner was like night and day.

Since the construction company does not want to alienate its customers and also wants to maintain a certain level, she was now replaced.
So completely normal reaction, right? The number of complaints was decisive and not just the problems I had.
Other customers also experienced errors in the building application. Heights and calculations were partly wrong. Her response to the Bauamt's (building authority's) notice was that the clerk was probably picky and shouldn't be so particular.
Professionalism at its finest

Good personnel are hard to find. Even for the authorities! Our official for the outdoor sauna project also kept making new demands. He even warned about the freelancer who filled out the building application. Well... in the end, his colleague processed the building application. Asked for one document and stamped it. 1.5 years of drama

That's true. Of course, that's the other side of the coin. It's terrible that as an end customer you are exposed to this and can't change anything.

The construction company then had to find a new one so that everything could continue at least halfway.

So you are not in a direct contractual relationship with the planner? Then I cannot understand your behavior; your contract partner is the construction company. They are responsible to you regarding costs, quality, and deadlines. Even if the subcontractor delivers poor work, the main contractor is primarily responsible as the contractual partner. The fact that they now want to shift the blame onto an employee or a subcontracting planner actually says a lot. If they want to handle things like that with all trades in the actual construction – good luck.

Did you read my post carefully? I don't think so

Counter-question:
Why are the many mentioned customer complaints not relevant?
What can the construction company do if the planner does not do her job properly?
What can the construction company do if the original planner who has been with the company for 20 years had a fatal accident?

Badmouthing the construction company is absolutely unrealistic and makes no sense at all!

If you only want to warn me because there are many unreliable construction companies that act as you describe, then you should communicate that exactly like that