Prefab basement made of element walls with internal insulation - experience?

Hello,
we are building a house with a prefabricated basement. The water exposure class is W 2.1 - Situation 1 (temporarily pressing stagnant water), soil sand/clay.

The base slab is made of waterproof concrete C25/30, the basement walls are precast concrete element walls with internal insulation which are poured again on site with concrete. Additionally, an external waterproofing is applied. Until now, I always thought this is a [Weiße Wanne]. This is also how it is advertised. However, if it is a [Weiße Wanne], then the concrete should provide the waterproofing, right? So why the external waterproofing? This is rather a [schwarze Wanne]. Furthermore, apparently no waterstop is installed between the base slab and the element wall, since the external waterproofing is carried over the joint between the wall and base slab down to the footing. Is that sufficient? Are there any experiences with such constructions?

Best regards, H.

we are building a house with a prefabricated basement. [...] Are there any experiences with such constructions?

There are dozens of experiences with white and black tanks and all kinds of other basements here in the forum, I couldn't even list them all. What does the other construction company, which continues from OKKD, say? - is the basement contracted through them, or did you dare to do it yourselves?

It all runs through the company … is the general contractor. They also provide the warranty at the end. And they have always been satisfied with the basement builder