Sorry the word sufficiently implies they did provide details for how they are going to take precautions… as the other person said I believe this is the definition of “complaints just for complaints sake” at least IMO

Environmental activists and other groups opposed to major construction projects in Germany have a tendency to latch on to even the most minor potential issue and complain and sue. The strategy, as far as I can infer it, is to delay the project and drive costs in the hope that it will have to be abandoned. It rarely works, but in combination with long and arduous processes for building permits, major construction projects can be held up in the planning phase for 10 to 20 years these days.

The Tesla factory is a huge exception, mostly because Tesla went ahead using temporary permits and took the risk that the final permits may be denied. The project has a lot of political support, which also helped the process along.

What evidence is there that it is a serious problem?

Lol.

On one end of the spectrum we have environmental groups making objections against every tiny detail.

On the other end we have - “Highly poisonous gas escaping the factory into the environment? What evidence is there that it is a serious problem?”. A very Nestle approach

TBF we have a claim that highly poisonous gas might escape.

I have no idea if thats true, how big the risks are or if things already have been cleared in the normal procedures.

This isn't the first factory in Germany and one would hope they know how to build them safely but who really knows.