Lighttpd may be listening on the port, but it is reported as failed in your debug log:
*** [ DIAGNOSING ]: Pi-hole processes
[✗] dnsmasq daemon is inactive
[✗] lighttpd daemon is failed
[✓] pihole-FTL daemon is active
Lighttpd and Apache2 can't both be on the same port 80. I believe your options will be:
- Uninstall/disable Apache2 and let lighttpd use port 80. Might not be a good solution for you if you have lots of services provided by Apache.
- Move lighttpd to another port. This change may be overwritten on any updates to Pi-Hole.
Related threads:
https://discourse.pi-hole.net/t/pi-hole-stats-are-resetting-to-zero-randomly/11729/5