Why Homebrew is connecting to Google analytics and how to disable it?

According to the official documentation : Anonymous Aggregate User Behaviour Analytics

Homebrew has begun gathering anonymous aggregate user behaviour analytics and reporting these to Google Analytics. You will be notified the first time you run brew update or install Homebrew.
Why?

Homebrew is provided free of charge and run entirely by volunteers in their spare time. As a result, we do not have the resources to do detailed user studies of Homebrew users to decide on how best to design future features and prioritise current work. Anonymous aggregate user analytics allow us to prioritise fixes and features based on how, where and when people use Homebrew.

You can disable this feature with :

brew analytics off

or by setting

export HOMEBREW_NO_ANALYTICS=1

The anonymizing flag is hardcoded as enabled, the Google Analytics anonymous IP setting, with further remarks:

It is impossible for the Homebrew developers to match any particular
event to any particular user, even if we had access to the Homebrew
analytics user ID (which we do not).

As far as we can tell it would be impossible for Google to match the
randomly generated Homebrew-only analytics user ID to any other Google
Analytics user ID. If Google turned evil the only thing they could do
would be to lie about anonymising IP addresses and attempt to match
users based on IP addresses.