What is the cause? Moisture problem in the plates

Dear forum participants

Excavated, filled up with 50cm, and now the slabs have been laid on gravel.
Obviously, we have a moisture problem.
Does anyone have any idea what could be the cause or have seen a similar case before?
Thank you very much

Lime gravel
Not compacted
Godelmann Tetrago paving

That is normal or will always be like that in the beginning

Thank you for the answer! We have paved another area, which was immediately "clear." Hence the uncertainty. May I ask if you are a professional?