diff --git a/packages/core/theme/core-theme-browser-mocks/src/theme_service.mock.ts b/packages/core/theme/core-theme-browser-mocks/src/theme_service.mock.ts
index e3d2b66645794..8c27cc8561cf7 100644
--- a/packages/core/theme/core-theme-browser-mocks/src/theme_service.mock.ts
+++ b/packages/core/theme/core-theme-browser-mocks/src/theme_service.mock.ts
@@ -14,7 +14,7 @@ import type { ThemeService } from '@kbn/core-theme-browser-internal';
 
 const mockTheme: CoreTheme = {
   darkMode: false,
-  name: 'amsterdam',
+  name: 'borealis',
 };
 
 const createThemeMock = (): CoreTheme => {
diff --git a/src/core/packages/rendering/server-internal/src/bootstrap/bootstrap_renderer.test.ts b/src/core/packages/rendering/server-internal/src/bootstrap/bootstrap_renderer.test.ts
index 7c1bbfc85c29f..8576d075c1fbc 100644
--- a/src/core/packages/rendering/server-internal/src/bootstrap/bootstrap_renderer.test.ts
+++ b/src/core/packages/rendering/server-internal/src/bootstrap/bootstrap_renderer.test.ts
@@ -35,13 +35,13 @@ const createPackageInfo = (parts: Partial<PackageInfo> = {}): PackageInfo => ({
 });
 
 const getClientGetMockImplementation =
-  ({ darkMode, name }: { darkMode?: boolean; name?: string } = {}) =>
+  ({ darkMode, name }: { darkMode?: boolean | string; name?: string } = {}) =>
   (key: string) => {
     switch (key) {
       case 'theme:darkMode':
         return Promise.resolve(darkMode ?? false);
       case 'theme:name':
-        return Promise.resolve(name ?? 'amsterdam');
+        return Promise.resolve(name ?? 'borealis');
     }
     return Promise.resolve();
   };
@@ -67,7 +67,7 @@ describe('bootstrapRenderer', () => {
     packageInfo = createPackageInfo();
     userSettingsService = userSettingsServiceMock.createSetupContract();
 
-    getThemeTagMock.mockReturnValue('v8light');
+    getThemeTagMock.mockReturnValue('borealislight');
     getPluginsBundlePathsMock.mockReturnValue(new Map());
     renderTemplateMock.mockReturnValue('__rendered__');
     getJsDependencyPathsMock.mockReturnValue([]);
@@ -124,7 +124,7 @@ describe('bootstrapRenderer', () => {
 
       expect(getThemeTagMock).toHaveBeenCalledTimes(1);
       expect(getThemeTagMock).toHaveBeenCalledWith({
-        name: 'v8',
+        name: 'borealis',
         darkMode: true,
       });
     });
@@ -141,7 +141,7 @@ describe('bootstrapRenderer', () => {
 
       expect(getThemeTagMock).toHaveBeenCalledTimes(1);
       expect(getThemeTagMock).toHaveBeenCalledWith({
-        name: 'v8',
+        name: 'borealis',
         darkMode: false,
       });
     });
@@ -167,7 +167,7 @@ describe('bootstrapRenderer', () => {
 
       expect(getThemeTagMock).toHaveBeenCalledTimes(1);
       expect(getThemeTagMock).toHaveBeenCalledWith({
-        name: 'v8',
+        name: 'borealis',
         darkMode: true,
       });
     });
@@ -192,7 +192,7 @@ describe('bootstrapRenderer', () => {
 
       expect(getThemeTagMock).toHaveBeenCalledTimes(1);
       expect(getThemeTagMock).toHaveBeenCalledWith({
-        name: 'v8',
+        name: 'borealis',
         darkMode: false,
       });
     });
@@ -217,7 +217,7 @@ describe('bootstrapRenderer', () => {
 
       expect(getThemeTagMock).toHaveBeenCalledTimes(1);
       expect(getThemeTagMock).toHaveBeenCalledWith({
-        name: 'v8',
+        name: 'borealis',
         darkMode: false,
       });
     });
@@ -247,7 +247,7 @@ describe('bootstrapRenderer', () => {
 
       expect(getThemeTagMock).toHaveBeenCalledTimes(1);
       expect(getThemeTagMock).toHaveBeenCalledWith({
-        name: 'v8',
+        name: 'borealis',
         darkMode: true,
       });
     });
@@ -290,13 +290,17 @@ describe('bootstrapRenderer', () => {
 
       expect(getThemeTagMock).toHaveBeenCalledTimes(1);
       expect(getThemeTagMock).toHaveBeenCalledWith({
-        name: 'v8',
+        name: 'borealis',
         darkMode: true,
       });
     });
 
     it('calls getThemeTag with the correct parameters when darkMode is `system`', async () => {
-      uiSettingsClient.get.mockResolvedValue('system');
+      uiSettingsClient.get.mockImplementation(
+        getClientGetMockImplementation({
+          darkMode: 'system',
+        })
+      );
 
       const request = httpServerMock.createKibanaRequest();
 
@@ -307,7 +311,7 @@ describe('bootstrapRenderer', () => {
 
       expect(getThemeTagMock).toHaveBeenCalledTimes(1);
       expect(getThemeTagMock).toHaveBeenCalledWith({
-        name: 'system',
+        name: 'borealis',
         darkMode: false,
       });
     });
@@ -321,7 +325,7 @@ describe('bootstrapRenderer', () => {
       });
     });
 
-    it('does not call uiSettingsClient.get', async () => {
+    it('does not call uiSettingsClient.get with `theme:darkMode`', async () => {
       const request = httpServerMock.createKibanaRequest();
 
       await renderer({
@@ -329,7 +333,7 @@ describe('bootstrapRenderer', () => {
         uiSettingsClient,
       });
 
-      expect(uiSettingsClient.get).not.toHaveBeenCalled();
+      expect(uiSettingsClient.get).not.toHaveBeenCalledWith('theme:darkMode');
     });
 
     it('calls getThemeTag with the default parameters', async () => {
@@ -367,7 +371,7 @@ describe('bootstrapRenderer', () => {
 
       expect(getThemeTagMock).toHaveBeenCalledTimes(1);
       expect(getThemeTagMock).toHaveBeenCalledWith({
-        name: 'v8',
+        name: 'borealis',
         darkMode: false,
       });
     });