How to figure out fees when moving coins between exchanges and wallets?

Hi all!
I would like to figure out a way to know how to best move coins between exchanges and wallets. This is not obvious and not clear to me. Is there a resource where I can get more educated on that?
For example, I just tried to transfer 30 USDT from Conibase Pro to Gateio. I was charged 7.9 USDT for that. This is crazy!!
Gateio offers a few channels, like Tron, or Polygon, etc., but the only one which seemed to work with Coinbase was ERC20 and that was 7.9 USDT.
So, how do you figure this out what to use and how to pay for that within a reason? Thank you!

Try NANO. It has very low fees.