Find all ACF image fields used on the site (including subfields) [WordPress]

find_acf_fields_by_type.php

//For example we need to modify all <img> tags in the templates that use ACF img fields. 
//To locate them in the theme we need to know their names.
//This snippet will list the names of all ACF fields of image type used on the site, so that we'll be able to search for them in the theme files

			$field_groups = acf_get_field_groups();
			$all_fields = array();
			foreach ($field_groups as $field_group){
				$fields = acf_get_fields($field_group['key']);
				$all_fields = array_merge($all_fields, $fields);
			}		
			$items = $all_fields;
			$all_img_subfields = [];			
			$all_img_fields = [];			
			foreach ($all_fields as $single_field){				
				if (!empty($single_field['sub_fields'])){					
					foreach($single_field['sub_fields'] as $repeater_sub_field){
						if ($repeater_sub_field['type'] === 'image'){
							$all_img_subfields[] = $repeater_sub_field['name'];
						}	
					}					
				}				
				if ($single_field['type'] === 'image'){
					$all_img_fields[] = $single_field['name'];
				}
			}
			echo "<br>ACF fields names of type image saved as fields:</br>";
			echo '<pre>'; print_r(array_unique($all_img_fields));  echo '</pre>'; 
			echo "<br>ACF fields names of type image saved as sub_fields:</br>";
			echo '<pre>'; print_r(array_unique($all_img_subfields)); echo '</pre>';