You can find your backups here:

Settings > scroll down to 'Security' > 'Backups'

Important note: After restoring a backup, you will need to log in with your Outbank ID and restore your subscription.

In case you use the data synchronisation between multiple devices, please reset the 'Secure Sync'. Every step of the way is described here: https://help.outbankapp.com/en/kb/articles/wie-kann-ich-den-secure-sync-zur-cksetzen-5

Tip:
The Secure Sync allows you to synchronize your data across different devices without manually editing and adding data. Read more about this here:
https://help.outbankapp.com/en/kb/articles/wie-kann-ich-mit-dem-secure-sync-auf-mehreren-ger-ten-parallel-nutzen