Tick it and Preview mode writes Google Tag logs into its Console tab. That is the same output the GA Debugger extension put in your browser console, so you can debug Google Analytics setups without the extension.
Google is moving logging into Tag Assistant instead of the extension. The extension was last updated in 2024 and will probably be deprecated at some point.
Watch out: the logs can't be exported yet and there are no filters by tag or template. They only live in the table in Tag Assistant.
Spotted by Simo Ahava.
