You have defined your local domain as lan in Pi-hole.
# The DNS domain used by your Pi-hole.
#
# This DNS domain is purely local. FTL may answer queries from its local cache and
# configuration but *never* forwards any requests upstream *unless* you have
# configured a dns.revServer exactly for this domain. In the latter case, all queries
# for this domain are sent exclusively to this server (including reverse lookups).
#
# For DHCP, this has two effects; firstly it causes the DHCP server to return the
# domain to any hosts which request it, and secondly it sets the domain which it is
# legal for DHCP-configured hosts to claim. The intention is to constrain hostnames so
# that an untrusted host on the LAN cannot advertise its name via DHCP as e.g.
# "google.com" and capture traffic not meant for it. If no domain suffix is specified,
# then any DHCP hostname with a domain part (ie with a period) will be disallowed and
# logged. If a domain is specified, then hostnames with a domain part are allowed,
# provided the domain part matches the suffix. In addition, when a suffix is set then
# hostnames without a domain part have the suffix added as an optional domain part.
# For instance, we can set domain=mylab.com and have a machine whose DHCP hostname is
# "laptop". The IP address for that machine is available both as "laptop" and
# "laptop.mylab.com".
#
# You can disable setting a domain by setting this option to an empty string.
#
# Possible values are:
# <any valid domain>
domain = "lan"
You also have this parameter set:
# If set, A and AAAA queries for plain names, without dots or domain parts, are never
# forwarded to upstream nameservers
domainNeeded = true ### CHANGED, default = false