I read somewhere that crypto.com haulted all the withdrawals so probably they are compensating with that by offering 0% commission for the trades? Not sure just a guess but anyhow you can ask the support if you really want to know the answer and if they say it happens just because of a glitch or something then you will be charged later yay 
Yeah i read about that last week, it's a successful hack attempt and many accounts were infected: https://decrypt.co/90590/crypto-com-suffers-hack-at-least-15m-ethereum
Then the exchange explained how the hack occurred, it seems like the option of withdrawal without going through 2FA procedure: https://ar.cointelegraph.com/news/crypto-com-finally-speaks-out-483-user-accounts-compromised?utm_source=Telegram&utm_medium=social
The exchange announced that he refunded all the infected users but there is no mention about allow users to withdraw with zero charges: https://crypto.com/product-news/crypto-com-security-report-next-steps
About OP, i can't figure out why he is asking about this like it's an issue in the exchange's system. If he thought the zero fees is an error, then just use it before the exchange discover it.