I did a similar thing with OKEx in 2018. Managed to accrue around $300,000 USD worth of BTC, but only managed to withdraw around $15k before I was permanently banned. Exchanges at the time and since aggressively market make their own books for various reasons, and were generally not careful back then about risk management.

In a strange twist I ended up doing some contract work for OKEx a few years later and was able to confirm some of the details about what they were doing on their end that led to the bad trades.