I have a flow that extends every meeting that I plan in my Outlook calendar to two other calendars.
Pretty straight forwared:

However, after it has run, the start time and the end time get updated. In most cases they get updated to start 1 hour sooner.
So, I did some research before posting and changed it to the following:

Wit in the functions the following:
convertTimeZone(triggerOutputs()?['body/Start'],'UTC', 'W. Europe Standard Time')
convertTimeZone(triggerOutputs()?['body/End'],'UTC', 'W. Europe Standard Time')
Now the even gets updated and starts an hour LATER than planned....
I don't think they all get updated. Some of the new items I insert using my phone, some using Outlook on the web, some using Outlook on my desktop and others using Outlook on my Surface Pro (also a desktop)