From Giki

Change blockingmode if redirects/site loading seems to hang

I've had the issue that some sources of some pages took ages to load. It was not until someone on Mastodon mentioned this very issue and that he fixed it by editing /etc/pihole/pihole-FTL.conf

source: https://docs.pi-hole.net/ftldns/blockingmode/

# default is NULL which answers with '' whereas 'NODATA' answers with empty responds 

and restart FTL service

sudo systemctl restart pihole-FTL.service

Delete query log history

source: https://github.com/pi-hole/pi-hole/issues/1992

#Flush logs does only delete the log of the current day.
#You can move/delete the long term history database:

cd /etc/pihole
sudo service pihole-FTL stop
sudo mv pihole-FTL.db pihole-FTL.db.old
sudo service pihole-FTL start