RESOLVED: with help from murmel on #ubuntu channel on libera platform, who wrote: hresco3: this is a configuration error, edit /ec/squid-deb-proxy/mirror-dstdomain.acl.d/01-default to allow your mirror

gistfile1.txt

## I used this recipe 
## https://fabianlee.org/2018/02/08/ubuntu-a-centralized-apt-package-cache-using-squid-deb-proxy/

## to set /etc/apt/apt.conf.d/00proxy on my client container 
## and to run squid-deb-proxy on my aptly server.   

## any thoughts on why this is not working?

# apt-get update 
Err:1 https://atl.mirrors.knownhost.com/mariadb/repo/10.6/ubuntu focal InRelease
  Invalid response from proxy: HTTP/1.1 403 Forbidden  Server: squid/3.5.27  Mime-Version: 1.0  Date: Sun, 30 Oct 2022 07:29:23 GMT  Content-Type: text/html;charset=utf-8  Content-Length: 3548  X-Squid-Error: ERR_ACCESS_DENIED 0  Vary: Accept-Language  Content-Language: en  X-Cache: MISS from squid-deb-proxy  X-Cache-Lookup: NONE from squid-deb-proxy:8000  Via: 1.1 squid-deb-proxy (squid/3.5.27)  Connection: keep-alive     [IP: 172.17.0.9 8000]
Err:2 http://apt.puppetlabs.com bionic InRelease                                          
  403  Forbidden [IP: 172.17.0.9 8000]
Err:3 http://ppa.launchpad.net/ondrej/php/ubuntu focal InRelease                          
  403  Forbidden [IP: 172.17.0.9 8000]
Err:4 http://ppa.launchpad.net/rmescandon/yq/ubuntu focal InRelease 
  403  Forbidden [IP: 172.17.0.9 8000]
Hit:5 http://archive.ubuntu.com/ubuntu focal InRelease
Get:6 http://archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
Get:7 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Get:8 http://archive.ubuntu.com/ubuntu focal-backports InRelease [108 kB]
Get:9 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages [2,737 kB]
Reading package lists... Done                                       
N: See apt-secure(8) manpage for repository creation and user configuration details.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
E: The repository 'http://apt.puppetlabs.com bionic InRelease' is no longer signed.
E: Failed to fetch http://apt.puppetlabs.com/dists/bionic/InRelease  403  Forbidden [IP: 172.17.0.9 8000]
E: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/dists/focal/InRelease  403  Forbidden [IP: 172.17.0.9 8000]
E: The repository 'http://ppa.launchpad.net/ondrej/php/ubuntu focal InRelease' is no longer signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://ppa.launchpad.net/rmescandon/yq/ubuntu/dists/focal/InRelease  403  Forbidden [IP: 172.17.0.9 8000]
E: The repository 'http://ppa.launchpad.net/rmescandon/yq/ubuntu focal InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.