Newb question: different fees for different transactions?

After buying through a centralized exchange for a while now I am finally starting to interact with the blockchain directly, but I am a little confused how the fees work. I was going to send some USDC to a wallet from my CEX so I have been watching gas fees on ehterscan and they are around $2.75 now. I went to start the transfer but the fee the exchange quoted was like $9. Where is the discrepancy coming from? Also, if I wanted to swap USDC for a different ERC20 token what kind of fee should I expect? Thanks for the help!