An investigation identified national security risks posed by a crypto facility in Wyoming. It is near an Air Force base and a data center doing work for the Pentagon.
That's the big environmental issue with Bitcoin — other major cryptocurrencies have moved to proof-of-stake instead of proof-of-work, so they don't need vast quantities of energy, and when you stop using all that energy, the generators with the highest marginal cost shut down, which generally means coal or gas.
A few months ago I read up on how much energy is used in a bitcoin transaction compared to a VISA transaction, it was something like 10000 times more energy for a bitcoin transaction
Currently. It's gone back and forth a few times, with each 'ban" preceding large purchases by the Chinese government of cryptocurrencies.
But even if it is illegal in China, they can hold the money offshore and spend it as easily as anybody else.
Also, if you are politically connected or pay the government enough money and your behavior doesn't negatively affect the CCP, then things aren't actionably illegal in China.