What is a “Style-Handle” is the style “ID”?

Hello – I am developing a site on a “Site Ground” server. The new WP install came with SG Optimizer plugin installed. Whether this plugin is active or inactive my development CSS is still being cached and it is making my css development almost impossible to do. So I see that there is a way to exclude a css file from being cached by adding the following to my functions.php file …

 add_filter( 'sgo_css_combine_exclude', 'css_combine_exclude' );
function css_combine_exclude( $exclude_list ) {
    // Add the style handle to exclude list.
    $exclude_list[] = 'style-handle';

    return $exclude_list;
}

add_filter( 'sgo_css_minify_exclude', 'css_minify_exclude' );
function css_minify_exclude( $exclude_list ) {
    // Add the style handle to exclude list.
    $exclude_list[] = 'style-handle';

    return $exclude_list;
}

But what is a style-handle? Is it the ID of the style LESS “-css”?

Example for this style:

<link rel='stylesheet' id='style-css' href='https://myurl/wp-content/themes/mytheme/style.css?ver=8.2.1' type='text/css' media='all' />

Would the following work…

$exclude_list[] = 'style';

And BTW I have tried the above and with using

$exclude_list[] = 'style-css';

… and neither has worked.

So does Site Ground have some other kind of caching going on that you might know of?