How thick is your floor slab? That looks like half a meter. Ours is supposed to be "only" 20 cm thick. I thought that was normal. By the way, we're finally starting too. The floor slab is supposed to be poured on Thursday - at 30 degrees. Do you actually have to water it or something?

Good eye. Our floor slab is about 25 cm thick, the rest is insulation, frost protection, and gravel. Basically, the thickness of the floor slab - to my knowledge - also depends on the KfW standard.
In addition, our slab had to be set a bit higher because our property was partly 70 cm below street level.
Only the frost protection was watered for compaction, the ground itself was not.