Moisture problems with Isover Vario Klimamembran KM Duplex UV

Hello everyone

we used the product Isover Vario Klimamembran KM Duplex UV 1.5 m x 40 m.
Which is supposed to be better than a PE foil.
In winter, no moisture rises into the insulation and in summer, the moisture can be released back to the indoor air.

The structure is as follows:

Uninsulated attic (with underlay membrane)
21mm tongue and groove boarding
240mm clamp fleece WLG 035 (between the rafters (rafters 240mm high)
Isover Vario Klimamembran KM Duplex UV
80mm wood fiber WLG 038
21mm air layer
12.5mm gypsum board

Now a friend said that moisture problems can occur with our structure.
Moisture would accumulate under the tongue and groove boarding.
With a PE foil this would not be the case, as it does not let moisture pass through.

Can this really happen or is the structure okay as it is?

Thank you very much for your opinion.

Best regards

Just also create an air layer under the [Rauspund]. Then the air can circulate there and the humidity will not accumulate too quickly. [Rauspund] is vapor permeable, meaning that if it is not too much in too short a time, the moisture can pass through it as well.