When setting up a recurring maintenance window (Daily/Weekly), it seems like UTC timezone gets used, however when choosing "One time only" it correctly uses my GMT+2 timezone.
I am currently experiencing this on 4.4.9 (zabbix/zabbix-web-nginx-mysql:alpine-4.4.9 & zabbix/zabbix-server-mysql:alpine-4.4.9 docker images).
My timezone is set to GMT+2 via environmental variable: PHP_TZ=Africa/Johannesburg
My Docker host is using UTC timezone.
However when hovering over the problem item, it can be seen that the maintenance window will suppress it till 09:14 instead, which means that it is working from UTC timezone and not my GMT+2 timezone:
It took me a while to pinpoint this issue, since the "One time only" maintenance periods work correctly in my timezone, and I've been wondering for a while now why my alerts are causing notifications almost 2 hours after my recurring maintenance window ends.