Ah is that definitely what it is?
I would wager 0.002 BTC that this is DEFINITELY what it is... especially if your Electrum wallet says [2fa] in the title bar next to the wallet name.
It is simply the prepayment for 20x 2FA transaction credits... if you click the little blue shield icon in the bottom right corner, you'll notice you now have 19 credits (your transaction used up one):