Fixed glazing plastic window is leaking

Based on the photos, I suspect that defects may be present, which in the worst case could even pose a danger to life and limb.

And your suspicion is so explosive that you don't want to put it into words?!

Instead, you bother to list who wrote what and when to show me that I could have had the answer much earlier, namely to approach the house construction company due to construction defects.

But it doesn't seem to be quite as unanimous as you write. See here:

Repairable: Yes, no problem, it is actually a small matter.

Sorry folks, but some are sitting on a pretty high horse here.
Of course, most of those who report problems here are laypeople. Otherwise, they would know the answer themselves.
At this point, everything is actually clear.
But just because someone is a layperson does not mean they are unskilled craft-wise. Or too stupid to read or something like that.
I once learned a metalworking trade and have done almost the entire house expansion alone.
And if things are explained to me properly, I understand them too.
But here many just throw down bits and expect you to know the rest.
Do you think people with problems in/at their house want to be explained stuff here in a somewhat hard to understand way?
One can write things differently and reasonably.
Why does it always have to come with such latent arrogance?

Hello, in image 613582-2-jpg, you can even see that a fastening point was not executed, there is a missing screw!!!

Was has the water ingress (already) been reported?

And the suspicion you have is so explosive that you don’t want to put it into words?!
Instead, you take the trouble to list who wrote what and when to show me
that I could have had the answer much earlier, namely to approach the house builder because of a construction defect.

Unfortunately, I (still can’t) definitively assess everything remotely based on photos and lay descriptions.
There are some points that can really only be checked on site (component opening). Speculations and assumptions don’t help you.
The brief summary does not claim to reproduce all opinions, rather these are the points that you should consider in my opinion.

Was the water ingress (already) complained about?
....
The brief summary does not claim to reproduce all opinions, rather these are, in my opinion, the points you should consider.

No, I'm going to sit down right now and write to the construction company.
Just to explain why I (and probably many others) are so very interested here in being able to fix the source of the error ourselves:
You probably all know the situation at the home improvement store. Endless waiting times, hardly any good craftsmen left,
frequently a reluctance to even accept jobs, etc.
And then you have to first fight out every complaint case with the construction company.
Being right and getting your rights are two different things. And they always hold the stronger position, for them the lawyers cost nothing,
because they have their own legal department etc.
And then maybe you get them to take care of the matter and then some botcher shows up and what could I have done? I once had my hallway painted as an insurance benefit (because other craftsmen messed it up while working in another room), only to paint it myself again immediately after the painter left. Because it all looked like crap.
And sometimes I prefer to do the work myself than to argue with someone forever and then still be annoyed afterward,
because the complaint is also a pain.
Ok, but in this case there is no doubt: the company has to look at it.

Especially, and now it's really not funny anymore:

Hello,
in image 613582-2-jpg, you can even see that a fastening point was not executed, there is a screw missing!!!

Not only is one screw missing in the window, but all of them are missing. As a result, I also found a second window in the house where this is the case. There, too, all the screw holes are empty.

So, thanks for the replies.

Moreover, and now it's really not funny anymore:

Not just one screw is missing in the window, but all of them. As a result, I also found a second window in the house
where this is the case. There, too, all the screw holes are empty.

So then, thanks for the answers.

Sure? Now you may/should/must take close-up shots.... because there are screw types that "disappear" in the profile... you can only see them, for example, if you shine a flashlight into the (apparently) empty hole.