We highly recommend creating frequent backups of your Reminder data. This will help you recover from unforeseen outages where your Reminder app becomes unusable and you have to uninstall the app & reinstall it.
Note: Based on the architecture of Rocket.Chat apps, once an app is uninstalled, then all its corresponding data automatically gets deleted - which means if you have users who have reminders created before an outage, those will be lost when you have to reinstall the app. In such a scenario, it is quite useful having a backup of your Reminder data so you can quickly recover from the outage and don't affect your workspace user's operation.