Modify Entity Reference Autocomplete Result In Drupal 8
In some cases we might need to modify the autocomplete result in Drupal 8. For example, when editing a node, in content authoring section, there is an autocomplete textfield for entering the author for the content. By default, all users will be available in the autocomplete list, but there might be a case when we need to exclude the blocked user from the list. Fortunately, we are able to do that by using one hook function called hook_query_alter.