The notebookDeprecated api proposal is currently not on track for finalization. It only contains a single property NotebookCellOutput.id, which we believe is no longer useful or needed

We plan on removing this proposal it once all current consumers have migrated off it. Here's the current list:

• Jupyter @rchiodo @DonJayamanne
• Data Wrangler @pwang347
• Dot Net Interactive @brettfo, @colombod

Please check if your extension is using this api and if you have any concerns migrating off of it