By default squid proxy server forwards the client IP address to the requested site, if you want the proxy to be surf users anonymously, you should send squid IP instead of clients IPs.

Change the forwarded_for option to off in /etc/squid/squid.conf file.

Add the following options mentioned here at the end of the configuration file.

<file bash /etc/squid/squid.conf> forwarded_for off </code>

sudo systemctl restart squid

You can check your public IP address, you will notice that your IP is the squid proxy server IP.