With the release of iOS 17, iPadOS 17, and macOS Sonoma, Apple now provides added privacy for Voice Memos users, by encrypting the titles of Voice Memos stored in iCloud, as well as the recordings themselves.
From Apple’s new support document:
How Voice Memos data is stored in iCloud
To protect your privacy and keep your personal information secure, your iCloud data—including Voice Memos recordings—is encrypted in transit and stored in an encrypted format.
Starting in iOS 17, iPadOS 17, and macOS Sonoma, the titles of your Voice Memos recordings that you store in iCloud are also encrypted.
Because of this additional encryption, when you update one of your Apple devices to iOS 17, iPadOS 17, or macOS Sonoma, your devices that you haven’t yet updated—with older versions of Voice Memos—may display the date and time of the recording (for example, “2023-08-11T07:53:31Z”) as the title, rather than the previous title of the recording.
If you can’t update your device to the latest software, the titles of Voice Memos recordings that you create on your updated device won’t sync to your old device.
(Via MacRumors)