I have the same issue and it occurs no matter what the “Ask to Join Networks” option is set to.
it automatically connects me to random wifi and there isn’t even a “Disconnect” option so the only way to disconnect is if I disable WiFi entirely. also if I disable “Auto-Join” it immediately turns back on.
I did find that these networks show up When I am on WiFi settings and I press “Edit” and I scroll down to “Managed Networks”
I cannot delete these networks, it seems like an invasion of privacy on Apple or the ISP’s part and neither of their support people understand.