i imagine they moved to bithumb due to acceptance of shady practices @bittrex and @poloniex will freeze coins for withdrawal and deposit if they see high holders are manipulating markets
I very much doubt that considering the people who were washtrading BCH on bithumb were arrested.
pretty sure no one was arrested for washtrading on @bithumb and when presented the evidence they denied it was happening at all.
which was funny considering 95% of daily trading volume was happening within a few minutes around 11 am
also in September bithumb had $350 million daily volume and by November was $11 billion over 12 times volume
for more on this
https://www.forbes.com/sites/johnkoetsier/2018/12/19/report-top-crypto-exchange-bithumb-faking-up-to-94-of-trading-volume-bithumb-denies-allegations/#523c135a645d
You're right, the article I found was about upbit apparently.
dodgy exchanges are easily confused