Fair price of USDT (and ETH) transfer

I am trying to figure out a fair price for sending USDT (ERC20) (I assume the same applies to Ethereum as well).

When I simulate the transaction on Trust Wallet, it says the "Network Fee" is $30.56. When doing the same on MetaMask, it indicates the "Estimated Gas Fee" is $15.38.

Upon consulting the Cost of Transaction Actions on etherscan.io, it mentions that the average cost of a "USDT transfer" transaction is $9.10.

How can we reconcile all this? What is a fair cost for this transaction? What should I expect?

Sorry if this is a beginner question.

Thank you.