Created attachment 201356 [details]
It's an RTL8821AU - driven by rtwn_usb(4) (however, I don't think this matters);
after some scan testing (wlandebug scan) I've done:
ifconfig wlan0 down
[~1 second pause]
ifconfig wlan0 destroy
The panic backtrace / kdb was shown instantly after the last command.
The backtrace has no net80211 / driver calls; I think it's something net-specific.
Comment on attachment 201356 [details]
I think this issue is another variant of:
Can you try the latest 13-current ?
Try this patch.
Everything is okay after update (r343473), thanks!