Would anyone know why when in a saved search using formula

TO_CHAR(SYS_EXTRACT_UTC(TO_TIMESTAMP_TZ(TO_CHAR({datecreated},'YYYY-MM-DD HH24:MI:SS'), 'YYYY-MM-DD HH24:MI:SS')), 'DD/MM/YYYY HH24:MI')

I end up with DD/MM results in September but for some reason in October I seem to get MM/DD?