Story time: The main fight around the environmental impact is the groundwater. Initial designs of Tesla planned to use up to 6.000.000 mยณ a year. As it comes from their own wells, it is free of charge. Under about a year of pressure, they got such crazy ideas, like actually recycling some of the water they use, cutting their planned usage in half.
A peak moment was Elon manically laughing and saying there is enough water in the region in an interview at the construction site. https://www.youtube.com/watch?v=ye8zcgxWMDc During this time the region was in the third year of an extraordinary drought.
Last year the local muncipal collective water company WSE (multiple muncipalities form a single muncipal company for water and wastewater) denied all permit for future development of housing, buildings, schools etc. as the budgeted ground water extraction is fully taken by Tesla. This lead to an attempt of some muncipal majors to topple the CEO and CFO of the muncipal company WSE which luckily failed.
Aside from the concerns about the total available water and the impact on the ground water table, another big issue are pollutants in the ground. There is a bubble of phenols from a former industrial site nearby. all the water plants around need to balance their water extraction to the bubble remains in place and isn't sucked into the groundwater table. For this there is also extensive pollutant monitoring at the wells in the region. Tesla denies the water company to get the data about pollutants that they measure at their own wells.
While the state government of Brandenburg is very lenient towards Tesla, having looked past multiple issues during the permit process, the water company and local people are fighting furiously to have these issues uncovered and discussed. The muncipalities are divided as seen in the failed attempt to kick out the CEO and CFO. While some of the local protest is classical NIMBYs most ist genuine concern about the impacts of the factory. As can be seen by the change in design, adressing issues early and providing a comprehensive strategy to make the plant possible, could have prevented much of the bad blood, but the state government and Tesla were eager to push through, no matter the costs.
Final remark: If the ground water table gets fucked with the pollutants mentioned earlier, this could affect water plants in Berlin, that provide drinking water to about a million people. It should be obvious that the only way to act here is in transparency and good faith, which so far was not in the interest of Tesla or the government of the state of Brandenburg.