ᐅ Roof terrace – pedestal supports – standing water

Hello,
I would like to hear your opinion.
We have a rooftop terrace in our new build.
The base is concrete. After that, I’m not sure what layers come next, but there is definitely an insulation layer. All of this is beneath a sealed membrane (I’m not sure what material this membrane is made of). There are drainage openings to allow rainwater to flow off, and there is also a slight slope.
On top of this membrane, pavers were installed using pedestal supports. Under each pedestal is a piece of matting (similar to the kind used under gym equipment), then a stone slab, and on top of that stone slab another piece of matting. The tiles you see are then installed continuously on top of this.
Today I removed two of these tiles to take a look underneath. It has rained heavily over the last two days, but not today. What struck me as odd is that there was quite a bit of standing water visible, which drains very slowly or not at all.
Is standing water problematic? Could it freeze in the worst case or damage the membrane?
Or is this completely normal and harmless?
The site management said in summer, before handover, that this is not a problem—the water will evaporate, and having some standing water is totally harmless for the materials.
One of the mats under the surface was even floating in the standing water...
Could this possibly be a defect and still considered a fault to report (if that is still possible)?
Thank you

If there is a slope and drainage, the water should flow away.
Are you referring to openings? As long as the building protection mats are only spot-installed, the drainage should not be obstructed.
I would say the slope is not appropriate.

Was there already standing water after rain before the terrace was built?
I wouldn’t want it like that.

Exactly, the openings refer to the drainage system.
The entire setup was designed with two drainage points, each located at the corners.
The mats are only installed at specific points.
Before everything was installed, some water was already pooling.
I questioned this several times. Then, as mentioned, the explanation given was that the water would evaporate. Since it was midsummer, the water did indeed evaporate quickly each time. Now, however, there have been several days of heavy rain.
I have attached some photos from the summer...
Thank you.
Do you consider this a defect?

The water seems to flow towards the drain. But could it be that the drain hole is positioned slightly too high? And that it either should have been placed more into the corner, or the slope coming from the corner should have been directed more towards the drain hole?

Possible, but I can’t really judge. How do you assess the situation? Could this become a problem, or is it simply an unattractive arrangement? Or is it actually a defect?