One note, neither wallet is charging me the 2FA fee for 20 transactions. I still have 10 paid.
One of your wallets must be trying to combine many small inputs in order to match your output's value. The more inputs you have, the more your transaction weights and the higher fee you have to pay. This article might help you to understand it more easily.
why when I am going to send the same amount of btc from each of them, at exactly the same time and to the same destination wallet, the fees are so different?
Good test. You pay the same number of satoshi/vbyte. Those vbytes are related to the size of the transaction. Not amount of money, instead the number of bytes of the transaction. It depends on the number of inputs (number of times you received that money you want to spend), number of outputs (number of addresses you send to) and also address type.
As an analogy, if you want to spend 5000$ made of 100$ bills is not difficult at all, but if you want to spend 5000$ made of 1 cent coins, you'll have to also pay for the truck that'll carry them.
Excellent explanation on the part of both. I have understood it now, by clicking on "advanced" I have been able to see the difference between the number of inputs and outputs of one operation and another.
They have helped me a lot, thank you!
