If the meeting time is also stored in UTC then both meeting time and reminder time get an updated display offset and are still the same time apart from each oth

If the meeting time is also stored in UTC then both meeting time and reminder time get an updated display offset and are still the same time apart from each other. Yes, the meeting time would be automatically changed from 4pm to 5pm in your timezone, but would have no change for people in other timezones. I would argue this is the expected behavior, and your app should notify users when timezones change which affect their meeting times.