lost voice memo app with all voice recordings

If you have a recent full backup, created before you deleted that app, you can restore data from it, keeping in mind that the "restore from backup" procedure overwrites all the current data on your iPhone.

No backup = No recovery, sorry

Regards

Giulio

iCloud should automatically create a backup if you performed the steps provided at section "Automatically back up with iCloud Backup" in this support guide:--> How to back up your iPhone, iPad, and iPod touch – Apple Support

And no, sorry there's no other way to retrieve those memo recordings. Unfortunately you underestimated the risk of not creating a backup on a regular basis.

Regards

Giulio