I don't know when this started to happen, it probably happened after an update to the pfsense or even the squid package, but I'm not sure of the exact moment.
Pfsense version: 2.5.2-RELEASE (amd64)
built on Fri Jul 02 15:33:00 EDT 2021
FreeBSD 12.2-STABLE
Squid package version: 0.4.45_4