Welcome to the thread. If you review previous entries, you will see that every few days, someone new shows up and basically posts the exact same thing you just posted.
There is no need to speculate about this: Apple has confirmed this is a bug in iOS.
No need to rehash, if you are curious just go a back a few pages in the thread and start reading. And if you don't feel like doing that, I can assure you it's a bug in iOS 8 and not generated by Google, because I have this bug and I don't use a single Google product for anything. My iOS devices sync to a MS Exchange server. I do use iOS 8.
When I create appointments using Outlook on my desktop computers, they stay at the correct times and don't get converted to GMT in Outlook, on my iPhone or on my iPad. When I create any appointment on any iOS device, it gets converted to GMT when it syncs over to my other device.
You use Google and I don't use Google at all yet we both have this same bug.....hmmmmm. That sort of confirms it isn't related to Google. We do both use iOS 8.....
Also, nothing has changed with the manner in which Google Calendar handles time zones. Yet there is no issue syncing to Google using pre 8.x versions of iOS...or any other mobile OS for that matter. Try it using a device using iOS 7.x. You will see that the very same appointment will remain at the correct time (i.e. the time you set it up for) on the iOS 7.x device, but that same appointment will transpose to GMT (or whatever timeszone your server's clock is set to) on the iOS 8.x device. The common factor for everyone experiencing this issue is that their devices are running iOS 8.
Then there's the many articles on the Internet about this confirming it's a bug (in Forbes etc.).
Now that you're here, you can watch the thread going forward and have deja vu when...in a few days, another new participant will show up and write essentially an identical post to the one you just wrote 🙂