iCloud Backup of iPhone no longer working despite sufficient storage.

My iPhone 13 recently stopped backing up despite sufficient storage. My backups are approximately 3GB and I'm on the 5GB plan. For years, my phone would back up every night, erasing the previous backup and storing the new one. Now, I am receiving an insufficient space error. I manually purged the old backup by turning off backups and deleting the existing backup, but it still says insufficient space. When I click on Settings, then my Apple ID, iCloud, Manage Account Storage, Backups, it shows 2.8GB used. However, when I click on Backups for more details, it shows 0KB for Documents & Data, and 0KB for iPhone backup. Only a few other KB of info gets stored in iCloud. Screen shots are below. So, here are the questions:

1. Even if this 2.8GB backup were still present somehow, why won't the new backup erase the old one like it did for years and years?
2. Why does Backups still show 2.8GB used even though there is no backup currently in iCloud?

Many thanks for any help!