Not that I don't believe you, because that looks very plausible to me, but do you happen to have any source/article on that would go into more details?
https://news.bitcoin.com/65-of-global-bitcoin-hashrate-conce...
https://www.forbes.com/sites/rogerhuang/2021/12/29/the-chine...
And more direct proof:
https://asia.nikkei.com/Spotlight/Caixin/How-illegal-online-...
https://www.thehindu.com/news/national/ed-arrests-cryptocurr...
https://www.forbes.com/sites/bryanrich/2019/05/14/bitcoin-is...
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From what I understand, there's two reasons Bitcoin money is popular in China. 1. Corrupt oligarchs with access to subsidized electricity can setup mining farms and basically print money. 2. Corrupt oligarchs with their money stuck in China can setup clandestine mining farms, and thereby exchange their yuans -> electricity/equipment -> BTC -> Vancouver/Sydney/London/...etc apartments.
I don't know if there are any good analyses of the volume of this trade, but the general assumption is that it's huge, the reason being that it's a relatively easy way around government restrictions.