You’ve done this: you’ve seen a public wifi and you’ve glommed onto it with barely a pause to send silent mental thanks to the shop that is providing it.
I do exactly that.
But I won’t log on to any site that way. The login details are not safe because there could well be something watching that apparently free wifi signal.
If it sounds like I’m building up to saying you should always pay for you wifi, I’m not. I’m building up to saying this: if you’re on your iPhone or Android device and you use a free public wifi, come off it to do anything sensitive.
Just tap the Wifi button off and your phone reverts to 4G and away you go.
Switch back to the free wifi to download something big or just browser faster. And if you do this a lot, consider paying for a VPN.