get acf fields by fieldgroup slug

get_acf_fields_by_fieldgroup_slug.php

<?php

// Note: [ACF Local JSON Sync](https://www.advancedcustomfields.com/resources/local-json/) must be set up for this strategy.
// Otherwise, just tweak the logic for detecting the field_group.

function _get_acf_fields_by_fieldgroup_slug( $slug ) {
  if ( !$slug ) return null;
  $acf_field_groups = acf_get_field_groups();
  $fields = [];
  foreach( $acf_field_groups as $group ) {
    if ( str_contains( $group['local_file'], $slug ) ) {
      $fields = acf_get_fields($group['ID']);
      break;
    }
  }
  return $fields;
}