In locales where the length of the name of the month of May is longer than three letters, rather than the short name of the month long display.
This is because in sequential replacement of names in the function "zbx_date2str" replacement of the month of May at the long name is always.
$output = str_replace(date('F',$value), $monthslong[date('n',$value)], $output);
Please Fix the logic of replacement names.
On locales EN, RU this bug is not visible (visible as normal).