A crypto exchange is a black box. As we learned last year with the collapses of FTX, Celsisus, and others, you often don't know what takes place at exchanges until it's too late.
Withdrawing to self-custody is the best way to have bitcoin you can audit on your own.
Crypto giant Binance commingled customer funds and company revenue, former insiders say
https://www.reuters.com/investigates/special-report/crypto-binance-money