Since 8.3.
For a text_field array type, we have a list of words based on which we output the AI icon if the element param name contains one of them. This filter is handy if you want to regulate this word library.
add_filter('wpb_module_ai_text_field_words', 'add_custom_ai_wpb_processor');
function add_custom_ai_wpb_processor(array $list): array {
$list[] = 'custom';
return $list;
}