I've seen some other people having an issue that the client receives reminders to Bookings with the wrong date or time. We have started having this problem too. It doesn't happen every time we schedule an appointment, so it's hard to replicate. For example, a client this morning scheduled an appointment for Feb 26th at 11am and the reminder shows 5am. Note that this seems to be happening for both email and text reminders.
I have made sure our general bookings page is in Mountain Standard time, and that all staff have their Outlooks set to Mountain Standard time. But we're still having this issue. Any help?! If this keeps going on we're going to stop using Bookings.
This looks like a very specific case that can be based on the settings configuration. I have tried to repro the same and unable to see any issues . Since we need some more data to understand the issue better , I would suggest to create a Microsoft support ticket so that we can be able to help better.