https://www.advancedcustomfields.com/resources/acf-format_value/
add_filter('acf/format_value/name=FIELD_NAME', 'MY_FUNCTION_NAME', 20, 3);
function MY_FUNCTION_NAME($value, $post_id, $field) {
$value = trim($field['prepend'].' '.$value.' '.$field['append']);
return $value;
}