After upgrading to Mac OS 15.3 Mac Pages no longer auto-saves.

Fails to autosave after initial save on the local drive or brand-x cloud service?

You will know if Pages v14.3 is not autosaving because there will be a black dot in the document's title bar red traffic light until you manually save again. If that dot does not appear, then autosaving is operational and happens about every ~10 seconds when changes are detected. Provided the save is to a supported filesystem.

One can prevent autosave in Pages on macOS v15.3 by enabling System Settings > Desktop & Dock > Ask to keep changes when closing documents ( ⚪️). If that is set, disable it.

You may need to save, close the document, and relaunch Pages after the above change for autosave to be reinstated in the application.

Unrelated to your normally functioning autosave, as long as you are making changes to your document and do not force a manual save, that "— Edited" will appear in the document title. This is normal.