[SOLVED] Pihole + Network Manager configuration

Your debug log shows dnsmasq running on port 53, and pihole-FTL not running.

*** [ DIAGNOSING ]: Ports in use
...
*:80 lighttpd (IPv4)
*:80 lighttpd (IPv6)
*:53 dnsmasq (IPv4)
*:53 dnsmasq (IPv6)

*** [ DIAGNOSING ]: Pi-hole processes
[✓] dnsmasq daemon is active
[✓] lighttpd daemon is active
[✓] pihole-FTL daemon is active

Why are you manually starting dnsmasq? pihole-FTL contains the required dnsmasq code (new to Pi-Hole V 4.0), so dnsmasq should not be running as a separate process.