Forum Academy Marketplace Showcase Pricing Features

Data loss in database

I’m experiencing certain data loss in my bubble app. I was testing my app with some data saved in the data base but every time when I return after some time a day later I find that bubble database no longer has some of the data I have registered when I was testing out the app. Is this a common issue or it’s an experienced by those on a free plan?

For future reference. How does one back up an app to avoid any data loss ?
thanks in advance