Why - php logged in user is root, not www-data?

[SLSCoder]

ubuntu 20.04 php 8.0
I'm using php-fpm to run php from apache2

The file: /etc/php/8.0/fpm/pool.d/www.conf shows:
user = www-data
group = www-data

The file: /etc/apache2/envvars shows:
export APACHE_RUN_USER=www-data
export APACHE_RUN_GROUP=www-data

The file: /etc/apache2/apache2.conf shows:
# These need to be set in /etc/apache2/envvars
User ${APACHE_RUN_USER}
Group ${APACHE_RUN_GROUP}

When I run a php file with this code in it:
echo get_current_user() . "<br>";

The response I get is: root

Why is the logged in user root instead of www-data and how can I reset it so that the logged in user is www-data?

Any help would be greatly appreciated.

[SLSCoder]

I changed the php code to:
echo $_SERVER['USER'] . "<br>";

The response this time was:
www-data

So now I'm confused.
Is the logged in user root or www-data?
I need the logged in user to be www-data, not root.

 

[requinix]

Read the documentation for get_current_user() and tell me what it says.

[SLSCoder]

OK I get it. thanks