Outlook wrong timezone when adding to calendar from Third Party App

Question

When I try to Add to Calendar from a third party app for meeting scheduling (SimplyBookMe), it is not translating the time zone correctly when I open up the calendar invite in Outlook. This is specifically surrounding dates around Daylight Savings Time. For example, I will book for 8AM Pacific Time and it will translate to 10AM Mountain Time which is incorrect (it's only a 1 hour time difference). Is there coding on the third party app that I should be checking to make sure SimplyBookMe and Outlook are communicating correctly?

Here are some screenshots to show the issue. As you can see, the tool is set to America/Los Angeles time zone (Pacific Time) and I have booked a time slot for 10:15AM PT.

I am currently in Mountain Time. When I click the Add to Calendar button, and Outlook, it downloads a calendar invite that is adding 2 hours to the time (and should be 1). This is where I am seeing the issue. It is adding an extra hour of time to the booking. I've had colleagues test it in CT and ET and the same issue happens where it is off by an hour.

The meeting is booked through the tool SimplyBookMe, which once you book it, it has an "Add to Calendar" button. I select Outlook, which then downloads a calendar invite. Once I open it up, that is where I am seeing the issue that the time zone has not translated correctly.

The timezone settings in my Outlook is Mountain Time.

I am using Microsoft 365 apps for enterprise.

I have already been working with the Third Party App to get this resolved, but they haven't been able to figure it out, which is why I'm hoping someone here has a solution that I can try! I think the question that it seems to be coming down to is whether they have coded the "Add to Calendar" feature correctly so that is speaks to Outlook correctly and adjusts to the right time. Since this issue is coming up around Daylight Savings Time, I am thinking there is coding that needs to be added to account for that. I did test out their Add to Calendar feature for Google Calendar and it works, so it really seems to be just the way it is speaking to Outlook calendar invites.