Hello centmarket,
Thanks for reaching out with your question, let me try to help you out here.
The timezone is actually (or should be) reflected. I ran a test on my site and gives me data like the following:
startDate 2017-05-03T22:00:00+00:00
This is the ISO 8601 time format and here the +00:00 signifies that this is UTC+00:00 timezone, so UTC.
When you are checking on google, how much are the starting and ending times off? Can you share some screenshots and urls so we can possibly investigate this further to see if we have a bug?
Thanks and cheers,
Andras