There are a number of unusual things in your debug log. Comparing to a bare metal install on Buster, same version of Pi-hole as you are running.
*** [ DIAGNOSING ]: php version
[✗] php version could not be detected.
What is the output of:
dpkg --list | grep php
*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[✗] Failed to resolve media-adrunner.mycomputer.com via localhost (127.0.0.1)
[✗] Failed to resolve media-adrunner.mycomputer.com via Pi-hole (192.168.1.186)
[✗] Failed to resolve doubleclick.com via a remote, public DNS server (8.8.8.8)
What his the output of the following command from the Pi terminal:
$ dpkg --list | grep php
ii php-cgi 2:7.3+69 all server-side, HTML-embedded scripting language (CGI binary) (default)
ii php-common 2:69 all Common files for PHP packages
ii php-sqlite3 2:7.3+69 all SQLite3 module for PHP [default]
ii php7.3-cgi 7.3.14-1~deb10u1 armhf server-side, HTML-embedded scripting language (CGI binary)
ii php7.3-cli 7.3.14-1~deb10u1 armhf command-line interpreter for the PHP scripting language
ii php7.3-common 7.3.14-1~deb10u1 armhf documentation, examples and common module for PHP
rc php7.3-fpm 7.3.14-1~deb10u1 armhf server-side, HTML-embedded scripting language (FPM-CGI binary)
ii php7.3-json 7.3.14-1~deb10u1 armhf JSON module for PHP
ii php7.3-opcache 7.3.14-1~deb10u1 armhf Zend OpCache module for PHP
ii php7.3-readline 7.3.14-1~deb10u1 armhf readline module for PHP
ii php7.3-sqlite3 7.3.14-1~deb10u1 armhf SQLite3 module for PHP