This use case should be solved by enabling the “Wi-Fi Assist” feature (which I believe is on by default) or avoided in the first place by turning off “Auto Join” for these networks - then you don’t even need to toggle WiFi.

In the same vain I regularly visit shopping malls. If I go in the week the WiFi usually works no issue, but at weekends when they are busy it can be very slow, so I usually turn off WiFi. With this feature I can still get location accuracy without using GPS (which saves battery) and don’t need to remember to turn it on when I’m home.

I don’t think there is anything wrong with the feature, but more the UI and feedback surrounding it. Someone else suggested pressing the button shows a pop up asking if you want to disconnect from the network, or turn off WiFi completely.