Uncaught Error: Non-static method globals::getInstance() cannot be called static

Debugging a custom WP theme and trying to update to WordPress 6 and PHP 8. Keep getting this error

Fatal error: Uncaught Error: Non-static method globals::getInstance() cannot be called statically in…functions.php

Here is the code block in question from my functions.php

function get_resource_cat_ids(){ 
	$IDArray = array(); 
	$resources_id = globals::getInstance()->resources_id; 
	$categories = get_categories(  array( 'parent' => $resources_id ) ); 
	foreach($categories as $cat) {    
		array_push($IDArray, $cat->term_id);	 
	} 	
	array_push($IDArray, $resources_id);
	return $IDArray;
}