Because the heavy positives come with some heavy negatives. China is an authoritarian nation that is making huge leaps and bounds here by using unilateral and undemocratic command to shift their nation state. They have near zero labor safety practices and are 100% happy to strip mine theirs or a foreign nation to get the resources to produce these important and valuable goods.
The heavy, direct influence of a billion+ person goverment dumping untold resources into producing EVs/Solar/etc at dirt cheap rates, then selling them, means that no other country can create it’s own independent industry in these very important products. That leaves climate change, and the worlds fate, in the hands of said authoritarian government, a, goverment that is still glad to spin up untold coal plants/oil plants/etc. That’s partly why tariffs have been springing up, although that’s also just flat out economic protectionism too.
Basically, China is brutally efficient here because they are brutal. Countires that are not cant compete or applaud this because its based on destruction of people, and democracies aren’t nominally a fan of that.
The other point here, past the brutality aspect, is that even if China was a shining example of democracy, you still don’t want one nation to be the only one that can produce these key climate change goods. Their oncoming recession is likely going to cause lots of issues with their progress here, so other countries spinning up these industries, even with teething pains, is a positive.