How much does MetaMask charge for ETH transfer?

Could you please clarify for me, how much does MetaMask typically levy as a fee for transferring Ethereum (ETH)? I'm interested in understanding the cost structure associated with this process, as I'm considering using MetaMask for my crypto transactions. Is the fee a fixed amount or does it vary based on certain factors like the amount of ETH being transferred or the current network congestion? Additionally, are there any hidden costs or additional fees that I should be aware of? Your insights would be greatly appreciated as I navigate the cryptocurrency landscape.