MacRumors published a story that Apple has released the third beta of macOS 14 Sonoma to registered developers.
Apple Seeds Third Beta of macOS 14 Sonoma to Developers
Apple today seeded the third beta of the upcoming macOS 14 Sonoma update to developers for testing purposes. The beta comes two weeks after the launch of the second beta.
Registered developers can download the beta through the Apple Developer Center and after the appropriate profile is installed, with the betas available through the Software Update mechanism in System Settings.