iCloud says Messages is 4GB, Messages says Messages is 10MB, apple support won't talk to me

My iphone has been giving me warnings that my icloud storage is full. The icloud page says Messages is consuming 3.8GB of 5GB. But when I click on Messages, Messages says Messages is only consuming a few MB. My Top Conversations are 10MB. I unsynced/resynced Messages multiple times. There are no images, no videos in any of my messages anywhere. Nothing but text. So 10MB sounds pretty reasonable to me. But whenever I resync Messages, icloud immediately says it is 3.8GB again. I do not have Messages synced to any other current or past devices. I previously contacted apple chat support and they said this is a known issue that they cannot fix, and I needed to talk to phone tech support. So I scheduled two calls with phone tech support, and twice phone support did not call me back at the scheduled time or at any subsequent time. So icloud is just broken, apple admits it's broken, and apple won't talk to me to fix it. WTF.