Source

File: wp-includes/theme.php

function get_theme_mods() {
	$theme_slug = get_option( 'stylesheet' );
	$mods       = get_option( "theme_mods_$theme_slug" );
	if ( false === $mods ) {
		$theme_name = get_option( 'current_theme' );
		if ( false === $theme_name ) {
			$theme_name = wp_get_theme()->get( 'Name' );
		}
		$mods = get_option( "mods_$theme_name" ); // Deprecated location.
		if ( is_admin() && false !== $mods ) {
			update_option( "theme_mods_$theme_slug", $mods );
			delete_option( "mods_$theme_name" );
		}
	}
	return $mods;
}