When updating from Illustrator 28.0 to 28.1, some preference files may be corrupted if AI is running certain 3rd party plugins. These include any written with Hot Door's CORE and incorporating a WebView widget to display a web page, but I have received reports of this behavior with some SDK plugins as well.

The problem it creates is that new files are not added to the File > Open Recent Files list, and any change to a different workspace is not saved.

For my macOS Ventura with AI 28.1, deleting these preference files solved the problem: Plug-in Cache and plugincache.bin.

For Windows 10 I had to also delete Adobe Illustrator Prefs and Adobe Illustrator Cloud Prefs.