Fail to work after installation
I really wish to help you on that. But I just installed it. Well in fact I started the install while VS2019 was running, then just before clicking the finale "Install" button, I closed VS2019. Then while in my Blazor project the output windows did not change in any way, and couldn't find any trace of the plug-in in VS option Windows. I ended up uninstalling it using the VS Extension manager. Hope this could help you.
Environment: Win 10 Build 2004 - French Canadien VS2019 v16.7.1 VS Language: English Project: C# Blazor Using VS Dark Mode UI

In my case I installed it on VS2015 Community Edition, both from outside VS and from within VS. Everything appeared to succeed and VS thinks that the extension is installed but I can find no other presence (Menu or dialog items) of the plugin within VS's user interface.
I'm also seeing exceptions in the activity log
<record>467</record>
<time>2024/03/09 03:18:49.152</time>
<type>Error</type>
<source>Microsoft.VisualStudio.CommonIDE.ExtensibilityHosting.VsShellComponentModelHost</source>
<description>A MEF Component threw an exception at runtime: Microsoft.VisualStudio.Composition.CompositionFailedException: An exception was thrown while initializing part "Balakin.VSOutputEnhancer.UI.FormatDefinitions.BuildResultSucceededFormatDefinition". ---> System.IO.FileNotFoundException: Could not load file or assembly 'Newtonsoft.Json, Version=7.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The system cannot find the file specified.
 at Balakin.VSOutputEnhancer.UI.StyleManager.LoadColorsFromResources()
 at System.Lazy`1.CreateValue()
 at System.Lazy`1.LazyInitValue()
 at System.Lazy`1.get_Value()
 at Balakin.VSOutputEnhancer.UI.StyleManager.GetStyleForClassificationType(String classificationType)
 at Balakin.VSOutputEnhancer.UI.FormatDefinitions.StyledClassificationFormatDefinition..ctor(IStyleManager styleManager)
 at Balakin.VSOutputEnhancer.UI.FormatDefinitions.BuildResultSucceededFormatDefinition..ctor(IStyleManager styleManager)
 --- End of inner exception stack trace ---
 at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.RuntimePartLifecycleTracker.CreateValue()
 at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.Create()
 at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.MoveNext(PartLifecycleState nextState)
 at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.MoveToState(PartLifecycleState requiredState)
 at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.GetValueReadyToExpose()
 at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0()</description>
</entry>
<entry>
<record>468</record>
<time>2024/03/09 03:18:49.168</time>
<type>Error</type>
<source>Editor or Editor Extension</source>
<description>Microsoft.VisualStudio.Composition.CompositionFailedException: An exception was thrown while initializing part "Balakin.VSOutputEnhancer.UI.FormatDefinitions.BuildResultSucceededFormatDefinition". ---> System.IO.FileNotFoundException: Could not load file or assembly 'Newtonsoft.Json, Version=7.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The system cannot find the file specified.
 at Balakin.VSOutputEnhancer.UI.StyleManager.LoadColorsFromResources()
 at System.Lazy`1.CreateValue()
 at System.Lazy`1.LazyInitValue()
 at System.Lazy`1.get_Value()
 at Balakin.VSOutputEnhancer.UI.StyleManager.GetStyleForClassificationType(String classificationType)
 at Balakin.VSOutputEnhancer.UI.FormatDefinitions.StyledClassificationFormatDefinition..ctor(IStyleManager styleManager)
 at Balakin.VSOutputEnhancer.UI.FormatDefinitions.BuildResultSucceededFormatDefinition..ctor(IStyleManager styleManager)
 --- End of inner exception stack trace ---
 at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.RuntimePartLifecycleTracker.CreateValue()
 at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.Create()
 at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.MoveNext(PartLifecycleState nextState)
 at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.MoveToState(PartLifecycleState requiredState)
 at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.GetValueReadyToExpose()
 at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0()
--- End of stack trace from previous location where exception was thrown ---
 at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0()
 at Microsoft.VisualStudio.Composition.DelegateServices.<>c__DisplayClass2_0`1.<As>b__0()
 at System.Lazy`1.CreateValue()
 at System.Lazy`1.LazyInitValue()
 at System.Lazy`1.get_Value()
 at Microsoft.VisualStudio.Text.Utilities.GuardedOperations.InstantiateExtension[TExtension](Object errorSource, Lazy`1 provider)</description>
</entry>
```