Vw says it's because some parts aren't available at the moment and that it will be configurable again in "the future".
Other sources say a batch of 5000 cars was planned and they are sold out...
I guess whe'll have to wait and see.
Do you have any source for those claims?
I’m saying this because after noticing the disappearance of the Edition 50 from the configurator I called several dealers. One told be that the car is not in the configurator because that it’s not yet on sale. Other told me that the disappearance was due to the fact that the Portuguese configurator was linked to the German one and since the model was removed from the German configurator automatically it was removed from the Portuguese one… Well, the removal from the German configurator didn’t happen yesterday…
Regarding your first statement, why only some configurators? Parts availability is common for every market I think.
Your last statement, we've had limited numbers in some models. Golf R 333 was limited to Germany with 333 units and all of those were sold out in 8 minutes. The Cupra Formentor VZ5 is once again in production and limited to 4000 units.

VW said that the model was going to be available all the year of 2026. I don't know 2026 means calendar year or Model Year.
In a German forum, someone mentioned the Instagram of Volkswagen and they keep posting things about the GTI Edition 50 and saying that the car is currently unavailable. Currently unavailable is different from sold out

I remember seeing a couple of months ago in the Belgium website that pre-sales would start and in the beginning of the year one could see one in dealers, test drive it and buy it. I don't think so judging by the way things are going...