Floor insulation not glued/sealed to the screed

The bonding of the panels and the edge strip is intended to prevent the panels from floating up.

Your mold problem (if there is one) is very unlikely to be related to this.

The bonding of the panels and the edge strip serves to prevent the panels from floating up.

Your mold problem (if there is one) is most likely not related to this.

I agree. 30-40% humidity stands on its own.

Nothing was glued here with us, but the entire underfloor heating was fixed differently. But underneath there are only Styrofoam boards

Nothing was glued here, but the entire underfloor heating was attached differently. But underneath there are only styrofoam boards.

The spacings look very large, or is it just an illusion? If not, you will always have to run a higher flow temperature than others, which you will notice in the heating costs. What is the heating system?

District heating, they have already complained that we require below average energy. The pipes were installed according to the calculation from the manufacturer. In the bathroom, the pipes lie close to each other because of the higher room temperature.

Why should the floor mold? The underfloor heating dries everything out. Mold doesn't stand a chance. The silverfish have a different origin.