Many thanks guys, I try to watch Pi-hole development closely but that one we obviously missed. Just fixed for next release: v8.0 · MichaIng/DietPi@cd3ac38 · GitHub
Do the following to fix it now:
curl -sSf 'https://raw.githubusercontent.com/MichaIng/DietPi/dev/.conf/dps_93/lighttpd.pihole.conf' -o /etc/lighttpd/conf-available/99-dietpi-pihole.conf
systemctl restart lighttpd
Nginx was as always a pain due to the fact that it does not inherit anything from parent location directives 
, took a while until I remembered that 
.
EDIT: Another fix for Nginx, now it really sets DENY when requested from anywhere else: v8.0 · MichaIng/DietPi@81aee17 · GitHub