Due to incorrect message processing Squid configured with append_domain can inappropriately redirect traffic to origins it should not be delivered to.
Created squid tracking bugs for this issue:
Affects: fedora-all [bug 1770367]
As per upstream:
Remove append_domain configuration settings from squid.conf.
The append_domain feature is redundant when /etc/resolv.conf is used to determine hostnames. However, please note that use of /etc/resolv.conf may require removal of dns_nameservers and other redundant DNS directives.