One issue is that the factory is located within the boundaries of the Wasserschutzgebiet Erkner/Neu Zittau, which means they have extra strict environmental safety requirements to avoid contaminating the water.

That seems like it could've been avoided, since Brandenburg doesn't have that many Wasserschutzgebiete: https://maps.brandenburg.de/apps/Wasserschutzgebiete/ (The WSG Erkner/Neu Zittau is the big blob south of Erkner, southeast of Berlin. If you zoom in far enough, you can see Tesla's factory at the blob's eastern border.)

Telsa knew very well about the Wasserschutzgebiet. The additional measures you have to take is not actually that relevant or expensive.

The location they ended up with, was suggested by the government of Brandenburg. It was one of a few locations.

And selecting a location has many, many, many factors. Tesla simply decided that the extra cost for that environment was less important then the other factors. Such as transportation infrastructure and likely many others.

Simply suggesting that they didn't know what they were doing because of the location they picked is not really defensible.

We also have no indication that the regulatory approval is delayed because of that specific issue.