If you want to know about the reorganization risk, use this tool for it:
https://jlopp.github.io/bitcoin-confirmation-risk-calculator/In most of the exchanges, a transaction must have 3-6 comfirmation before your transaction can be consider deposit. They don't release Bitcoin you deposit until that comfirmation is reach before they allow you to do anything with that Bitcoin, you may be allow to trade it with one comfirmation but you can't withdraw it unless that comfirmation is complete. Why?
hosseinimr93 has answered your question already but on most world standard exchanges, the deposit can be 1 confirmation but the withdrawal is not more than 2 or 3 confirmations. The exchange that I have used that required 10 confirmation was in 2020 but most exchanges have reduced the confirmation needed for bitcoin confirmation.