Thanks everyone for chiming in and trying to help.
I would like to state here that I am in no way frustrated with the VV or the company/manufacturer behind it.
I'd rather have someone do their thing, keep it local and stand behind it for the positive and negative feedback than some kind of hit & run company with offices in countries I don't even know (exaggeration) and nonexistent customer support.
from a recent exchange with a seller from low-end vape (paraphrased but not exaggerated):
"yes dear, black and green were out of order, so we sent you purple one. it looks great too hope you likey!1!1 want to special price for new order of black one?"
Noooooooooooo! Bad business. Would have ordered more if they were honest.
Back on topic:
Taking out the square mesh over the hole didn’t change much, maybe 10% better airflow.
I read about the sealing not being tight around the glass dome, so I put some tape around the part where it screws in (as described by meduser#420) and had about a 50% increase of vapor.
For the first time I could see the air going through the herb chamber from below and then passing down on the glass, more or less into the hole and into the tube.
The result is still far away from what I am used to from the pax, so I conclude that it is still not working properly.
At least we narrowed down the reason: Air leakage. Probably around the glass dome or around the heating element.
Another point to note: After making the sealing around the glass a littler better I blew into the tube again the see where the vapor would go. Part of it came outside the hole next to the charger inlet.
Now, at this point I don't feel comfortable with modding the unit by myself. Obviously something is off the norm. Might be from shipping, might be a rookie-mistake of the assistant manufacturer or it might be technical malfunction of some components. $hit happen$.
I'll be in touch with Ville to sort things out.
Again thanks to everyone involved.
@PPN I don't think you have anything to worry about if your unit is assembled correctly and not malfunctioning.
@Squonk regarding the circlip: I was thinking the same, that it should be on top of the ss to give it more of a sealing than if it is below, but I think that it is meant to be below the ss to prevent the cover from falling off the bulb and into the glass dome (when turned upside down for example).
@RUDE BOY The herb chamber isn't actually present in the pictures I uploaded, that's the cover of the light bulb, which is mounted by the herb chamber. They look similar.