Hey there, cleesi!
Thanks so much for using Apple Support Communities.
Have you had a chance to reinstall Voice Memos and see if you can manually delete any data from inside that app? It's possible that the app has been deleted but for some reason, some data has been left on the device. If you haven't tried that yet, we'd advise doing so and seeing if it helps resolve this issue for you.
Another good step would be rebooting your iPhone and then checking storage again to see if that helps refresh the data allotment information.
We hope that this information is helpful.
Have a great day!