diff --git a/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts b/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts
index 1231c27746c..574164861e5 100644
--- a/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts
+++ b/src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts
@@ -8,7 +8,7 @@ import { Emitter, Event } from 'vs/base/common/event';
 import { Disposable, dispose, IDisposable } from 'vs/base/common/lifecycle';
 import { URI } from 'vs/base/common/uri';
 import { NotebookCellTextModel } from 'vs/workbench/contrib/notebook/common/model/notebookCellTextModel';
-import { INotebookTextModel, NotebookCellOutputsSplice, NotebookDocumentMetadata, NotebookCellMetadata, ICellEditOperation, CellEditType, CellUri, notebookDocumentMetadataDefaults, diff, NotebookCellsChangeType, ICellDto2, TransientOptions, NotebookTextModelChangedEvent, NotebookRawContentEvent, IOutputDto, ICellOutput, IOutputItemDto, ISelectionState, NullablePartialNotebookCellMetadata, NotebookCellInternalMetadata, NullablePartialNotebookCellInternalMetadata } from 'vs/workbench/contrib/notebook/common/notebookCommon';
+import { INotebookTextModel, NotebookCellOutputsSplice, NotebookDocumentMetadata, NotebookCellMetadata, ICellEditOperation, CellEditType, CellUri, diff, NotebookCellsChangeType, ICellDto2, TransientOptions, NotebookTextModelChangedEvent, NotebookRawContentEvent, IOutputDto, ICellOutput, IOutputItemDto, ISelectionState, NullablePartialNotebookCellMetadata, NotebookCellInternalMetadata, NullablePartialNotebookCellInternalMetadata } from 'vs/workbench/contrib/notebook/common/notebookCommon';
 import { IUndoRedoService, UndoRedoElementType, IUndoRedoElement, IResourceUndoRedoElement, UndoRedoGroup, IWorkspaceUndoRedoElement } from 'vs/platform/undoRedo/common/undoRedo';
 import { MoveCellEdit, SpliceCellsEdit, CellMetadataEdit } from 'vs/workbench/contrib/notebook/common/model/cellEdit';
 import { ISequence, LcsDiff } from 'vs/base/common/diff/diff';
@@ -197,7 +197,7 @@ export class NotebookTextModel extends Disposable implements INotebookTextModel
 	private _cellListeners: Map<number, IDisposable> = new Map();
 	private _cells: NotebookCellTextModel[] = [];
 
-	metadata: NotebookDocumentMetadata = notebookDocumentMetadataDefaults;
+	metadata: NotebookDocumentMetadata = {};
 	transientOptions: TransientOptions = { transientCellMetadata: {}, transientDocumentMetadata: {}, transientOutputs: false };
 	private _versionId = 0;
 
diff --git a/src/vs/workbench/contrib/notebook/common/notebookCommon.ts b/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
index 78f38d3f33c..78cb628688a 100644
--- a/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
+++ b/src/vs/workbench/contrib/notebook/common/notebookCommon.ts
@@ -60,14 +60,7 @@ export enum NotebookRunState {
 	Idle = 2
 }
 
-export const notebookDocumentMetadataDefaults: Required<NotebookDocumentMetadata> = {
-	custom: {},
-};
-
-export interface NotebookDocumentMetadata {
-	custom?: { [key: string]: unknown; };
-	[key: string]: unknown;
-}
+export type NotebookDocumentMetadata = Record<string, unknown>;
 
 // Aligns with the vscode.d.ts version
 export enum NotebookCellExecutionState {
diff --git a/src/vs/workbench/contrib/notebook/test/notebookViewModel.test.ts b/src/vs/workbench/contrib/notebook/test/notebookViewModel.test.ts
index 78f6e82be8a..72b861ed3be 100644
--- a/src/vs/workbench/contrib/notebook/test/notebookViewModel.test.ts
+++ b/src/vs/workbench/contrib/notebook/test/notebookViewModel.test.ts
@@ -20,7 +20,7 @@ import { NotebookEventDispatcher } from 'vs/workbench/contrib/notebook/browser/v
 import { NotebookViewModel } from 'vs/workbench/contrib/notebook/browser/viewModel/notebookViewModel';
 import { ViewContext } from 'vs/workbench/contrib/notebook/browser/viewModel/viewContext';
 import { NotebookTextModel } from 'vs/workbench/contrib/notebook/common/model/notebookTextModel';
-import { CellKind, diff, notebookDocumentMetadataDefaults } from 'vs/workbench/contrib/notebook/common/notebookCommon';
+import { CellKind, diff } from 'vs/workbench/contrib/notebook/common/notebookCommon';
 import { NotebookOptions } from 'vs/workbench/contrib/notebook/common/notebookOptions';
 import { ICellRange } from 'vs/workbench/contrib/notebook/common/notebookRange';
 import { NotebookEditorTestModel, setupInstantiationService, withTestNotebook } from 'vs/workbench/contrib/notebook/test/testNotebookEditor';
@@ -37,7 +37,7 @@ suite('NotebookViewModel', () => {
 	instantiationService.stub(IThemeService, new TestThemeService());
 
 	test('ctor', function () {
-		const notebook = new NotebookTextModel('notebook', URI.parse('test'), [], notebookDocumentMetadataDefaults, { transientCellMetadata: {}, transientDocumentMetadata: {}, transientOutputs: false }, undoRedoService, modelService, modeService);
+		const notebook = new NotebookTextModel('notebook', URI.parse('test'), [], {}, { transientCellMetadata: {}, transientDocumentMetadata: {}, transientOutputs: false }, undoRedoService, modelService, modeService);
 		const model = new NotebookEditorTestModel(notebook);
 		const viewContext = new ViewContext(new NotebookOptions(instantiationService.get(IConfigurationService)), new NotebookEventDispatcher());
 		const viewModel = new NotebookViewModel('notebook', model.notebook, viewContext, null, instantiationService, bulkEditService, undoRedoService, textModelService);
diff --git a/src/vs/workbench/contrib/notebook/test/testNotebookEditor.ts b/src/vs/workbench/contrib/notebook/test/testNotebookEditor.ts
index 0c191ba054f..2e25b129586 100644
--- a/src/vs/workbench/contrib/notebook/test/testNotebookEditor.ts
+++ b/src/vs/workbench/contrib/notebook/test/testNotebookEditor.ts
@@ -21,7 +21,7 @@ import { NotebookEventDispatcher } from 'vs/workbench/contrib/notebook/browser/v
 import { CellViewModel, NotebookViewModel } from 'vs/workbench/contrib/notebook/browser/viewModel/notebookViewModel';
 import { NotebookCellTextModel } from 'vs/workbench/contrib/notebook/common/model/notebookCellTextModel';
 import { NotebookTextModel } from 'vs/workbench/contrib/notebook/common/model/notebookTextModel';
-import { CellKind, CellUri, INotebookDiffEditorModel, INotebookEditorModel, IOutputDto, IResolvedNotebookEditorModel, NotebookCellMetadata, notebookDocumentMetadataDefaults } from 'vs/workbench/contrib/notebook/common/notebookCommon';
+import { CellKind, CellUri, INotebookDiffEditorModel, INotebookEditorModel, IOutputDto, IResolvedNotebookEditorModel, NotebookCellMetadata, } from 'vs/workbench/contrib/notebook/common/notebookCommon';
 import { ICellRange } from 'vs/workbench/contrib/notebook/common/notebookRange';
 import { TextModelResolverService } from 'vs/workbench/services/textmodelResolver/common/textModelResolverService';
 import { IModelService } from 'vs/editor/common/services/modelService';
@@ -176,7 +176,7 @@ function _createTestNotebookEditor(instantiationService: TestInstantiationServic
 			outputs: cell[3] ?? [],
 			metadata: cell[4]
 		};
-	}), notebookDocumentMetadataDefaults, { transientCellMetadata: {}, transientDocumentMetadata: {}, transientOutputs: false });
+	}), {}, { transientCellMetadata: {}, transientDocumentMetadata: {}, transientOutputs: false });
 
 	const model = new NotebookEditorTestModel(notebook);
 	const viewContext = new ViewContext(new NotebookOptions(instantiationService.get(IConfigurationService)), new NotebookEventDispatcher());