Publishing is an optional and additional action during the save process. When you publish changes, the files associated with the account profile are regenerated to include the current configuration. It typically takes a few minutes after the publish for the files to update.
Publish environments provide separate instances of the Universal Tag (utag.js) to install on your production and non-production sites. There are three publish environments to support a proper release cycle: *Dev, QA, and Prod. Each environment uses a separate file for your different website environments. Using separate environments allows you to test changes before releasing them directly to your production site.
There are three default publish environments which correspond to three instances of the Universal Tag (utag.js):
An environment for developing new tags and features.
An environment for testing and validation.
The environment of your live production site.
For example, the file from the Prod environment should be installed on your production site: