ᐅ Flat roof vapor barrier – this isn’t correct, is it?

Hello,

So far, we have had issues with almost every tradesperson...
Now the roofer has started.
First, they installed the rafters. A few of them are too long and press down on the insulation.
I’m letting that slide for now... Also, the roof decking is already in place.
Of course, they forgot to remove the protective film from the glued laminated timber beams...
So now I have to remove the film myself with a utility knife... Great.

Now to the main problem...
As far as I understand, a vapor barrier must be installed over the roof decking—this MUST BE AIRTIGHT, right? Or am I mistaken?
On top of that comes the tapered insulation, and then this roofing felt is welded on, correct?

And now please tell me your opinion about the vapor barrier... it has been installed terribly.
Or can it be left as is?

Please get an expert who can also tell you exactly how precise it needs to be... no one here can really provide that.