New construction - now or wait? Experiences?

If something like that comes up again, is a ground survey always the deciding factor?

Yep. If there are signs, only buy with an expert report. Otherwise, you might face up to 50k (estimate) in additional costs that no one expects.
But maybe there are also options with screw foundations or other alternatives.

I found out that a friend knows the neighbor of the property. She then asked him about the property: The soil is apparently very peaty (peat was also extracted not far away in the past). [ / ] How do you actually assess peaty or sandy soil? From what I have read so far, these are unpredictable soil structures that require special planning. If we come across something like this again, a soil survey is probably always crucial?

If there are signs, buy only and exclusively with a survey. Otherwise, in doubt, there can be up to 50k (estimate) additional costs that no one expects.

In other cases, do use such a contact to ask the neighbor about their foundation work (as said, forget this offer otherwise). Building on sand is the origin of a proverb, and peat is different but similarly unfavorable as building ground. Soil surveys (preferably before purchase) are generally sensible – that is, even without suspicion of any malignancy of the building ground.

What I have read so far are unpredictable soil structures that require special planning.

I have only read that the costs can be exorbitant: soil replacement or pile construction.

Edit: all my former places of residence are also within a radius of about 3km from my current one.

Phew, that is still very location-bound. Our current house is about 30km away from our first house. And other rental properties are located within a radius of just under 150km. However, we are currently reducing those and investing abroad due to the uncertain political and economic situation here.

Phew, that is still very location-bound. Our current house is about 30km away from our first residence. And further rental properties are located within a radius of almost 150km. However, we are currently reducing those and investing abroad due to the uncertain political and economic situation here.

That happened in due time

but I mentioned it as a response to the argument that the neighborhood also changes when you move to a different house/apartment.

I wanted to show that it does not necessarily have to change.

Hello everyone,
there have been some new developments. We have received a soil report for the property.
The report is attached. The names of private individuals who apparently commissioned the report are redacted.
What confuses me is the headline: "preliminary initial assessment."
Overall, the report looks okay to me, meaning less severe than expected.
What still stands out is that the load-bearing capacity is assessed as low to very low - what does that mean?
There are also many subjunctive forms like "should, would, etc." For example: should strongly clayey soils with peat-containing components or silt lenses occur in the area of the foundation bases, the soil must be completely removed.
Even with the report, there still seem to be greater uncertainties regarding soil replacement...

What do you all think?