iCloud Messages app storage discrepancy on iPhone

In my iCloud storage, the messages app takes up 93.4 GB of storage. However, when I click into it there are only 15.16 GB of messages saved to my phone. I try to delete messages to get storage back, but it does nothing. I don't understand why there is so much storage being taken up in iCloud. How do I get some of the storage back?

[Re-Titled by Moderator]

Original Title: Messages and iCloud Storage