Hello prisila130,
Thanks for posting in Apple Support Communities. Restoring app content may not be available. And if available, it would require restoring your iPhone from the backup and would erase all content added after that date. You can check to see whether you have an iCloud backup by taking the following steps from Locate backups of your iPhone, iPad, and iPod touch - Apple Support.
"On your iPhone, iPad, or iPod touch:
- Go to Settings > [your name] > iCloud.
- Tap Manage Storage, then tap Backups.
- Tap a backup to see more details about it, choose which information to back up, or delete the backup."
Also, even with a backup in place, your app would only have been backed up if it was enabled from Settings > [Your name] > iCloud > Manage Storage (or Manage Account Storage) > [App name].
Since this is a third-party app, the developer may have further suggestions. If you'd like to reach out to them, the guidance in How to contact an app developer - Apple Support can help.
Take care.