I presume it is the uncertainty that is the real issue. Nobody likes surprises. In some ways the cobalt tax has nothing and everything to do with NZC. The PFS basically did not include cobalt, yet a lot of focus moving forward for Stage 2 will be around cobalt.
Just for comparison Namibia (where another cobalt ASX company lies) has a mining tax of 37.5% compared to 30% in the DRC. Factoring in royalties the DRC will still remain a cheaper country to do business. Most African countries demand a 10% government stake in mining projects. The proposed copper royalty tax is also within the range imposed by many governments in the region, such as Zambia (6%), Ghana (5%) and Tanzania (4%). The super profits tax is where the uncertainty lies.