Pi-Hole has two logs/databases. You have turned off logging to one of the two.
The pihole.log is toggled with the pihole -l command and on the Admin GUI (settings > System) in the orange box labeled "Disable Query logging."
pihole -l -h
Usage: pihole logging [options]
Example: 'pihole logging on'
Specify whether the Pi-hole log should be used
Options:
on Enable the Pi-hole log at /var/log/pihole.log
off Disable and flush the Pi-hole log at /var/log/pihole.log
off noflush Disable the Pi-hole log at /var/log/pihole.log
There is a second file, the long term database, that stores data for a default of 365 days. This database is controlled from commands in the /etc/pihole/pihole-FTL.conf file.
You can verify the size of your files and access dates to see if they are active:
stat /etc/pihole/pihole-FTL.db
stat /var/log/pihole.log
The documentation below discusses the long term database and configuration options.