As for currently enforcing this, @htdvisser wrote on Slack July 3rd:
But no, we’re indeed not enforcing it at the moment
It’s pretty difficult to detect (with certainty) that a device is hardcoded to SF11/SF12
Sure, we can “assume” it if a device with a good signal is transmitting on SF12
But in my opinion, we should first notify the owner before we start blocking a device
And we’re still working on this notification system