diff --git a/src/EditorFeatures/CSharpTest/Diagnostics/DiagnosticAnalyzerDriver/DiagnosticAnalyzerDriverTests.cs b/src/EditorFeatures/CSharpTest/Diagnostics/DiagnosticAnalyzerDriver/DiagnosticAnalyzerDriverTests.cs
index cc31be1188cb3..c4f33d130bbb8 100644
--- a/src/EditorFeatures/CSharpTest/Diagnostics/DiagnosticAnalyzerDriver/DiagnosticAnalyzerDriverTests.cs
+++ b/src/EditorFeatures/CSharpTest/Diagnostics/DiagnosticAnalyzerDriver/DiagnosticAnalyzerDriverTests.cs
@@ -656,28 +656,21 @@ await TestNuGetAndVsixAnalyzerCoreAsync(
         //   1) No duplicate diagnostics
         //   2) Both NuGet and Vsix analyzers execute
         //   3) Appropriate diagnostic filtering is done - Nuget suppressor suppresses VSIX analyzer.
-        //
-        // 🐛 After splitting fallback options into separate CompilationWithAnalyzers for project and host analyzers,
-        // NuGet-installed suppressors no longer act on VSIX-installed analyzer diagnostics. Fixing this requires us to
-        // add NuGet-installed analyzer references to the host CompilationWithAnalyzers, with an additional flag
-        // indicating that only suppressors should run for these references.
-        // https://github.com/dotnet/roslyn/issues/75399
-        const bool FalseButShouldBeTrue = false;
         await TestNuGetAndVsixAnalyzerCoreAsync(
             nugetAnalyzers: ImmutableArray.Create(firstNugetAnalyzer),
             expectedNugetAnalyzersExecuted: true,
             vsixAnalyzers: ImmutableArray.Create(vsixAnalyzer),
             expectedVsixAnalyzersExecuted: true,
             nugetSuppressors: ImmutableArray.Create(nugetSuppressor),
-            expectedNugetSuppressorsExecuted: FalseButShouldBeTrue,
+            expectedNugetSuppressorsExecuted: true,
             vsixSuppressors: ImmutableArray<VsixSuppressor>.Empty,
             expectedVsixSuppressorsExecuted: false,
             new[]
             {
                 (Diagnostic("A", "Class").WithLocation(1, 7), nameof(NuGetAnalyzer)),
-                (Diagnostic("X", "Class", isSuppressed: FalseButShouldBeTrue).WithLocation(1, 7), nameof(VsixAnalyzer)),
-                (Diagnostic("Y", "Class", isSuppressed: FalseButShouldBeTrue).WithLocation(1, 7), nameof(VsixAnalyzer)),
-                (Diagnostic("Z", "Class", isSuppressed: FalseButShouldBeTrue).WithLocation(1, 7), nameof(VsixAnalyzer))
+                (Diagnostic("X", "Class", isSuppressed: true).WithLocation(1, 7), nameof(VsixAnalyzer)),
+                (Diagnostic("Y", "Class", isSuppressed: true).WithLocation(1, 7), nameof(VsixAnalyzer)),
+                (Diagnostic("Z", "Class", isSuppressed: true).WithLocation(1, 7), nameof(VsixAnalyzer))
             });
 
         // Suppressors with duplicate support for VsixAnalyzer, but not 100% overlap. Verify the following:
@@ -691,15 +684,15 @@ await TestNuGetAndVsixAnalyzerCoreAsync(
             vsixAnalyzers: ImmutableArray.Create(vsixAnalyzer),
             expectedVsixAnalyzersExecuted: true,
             nugetSuppressors: ImmutableArray.Create(partialNugetSuppressor),
-            expectedNugetSuppressorsExecuted: FalseButShouldBeTrue,
+            expectedNugetSuppressorsExecuted: true,
             vsixSuppressors: ImmutableArray.Create(vsixSuppressor),
             expectedVsixSuppressorsExecuted: false,
             new[]
             {
                 (Diagnostic("A", "Class").WithLocation(1, 7), nameof(NuGetAnalyzer)),
                 (Diagnostic("X", "Class", isSuppressed: false).WithLocation(1, 7), nameof(VsixAnalyzer)),
-                (Diagnostic("Y", "Class", isSuppressed: FalseButShouldBeTrue).WithLocation(1, 7), nameof(VsixAnalyzer)),
-                (Diagnostic("Z", "Class", isSuppressed: FalseButShouldBeTrue).WithLocation(1, 7), nameof(VsixAnalyzer))
+                (Diagnostic("Y", "Class", isSuppressed: true).WithLocation(1, 7), nameof(VsixAnalyzer)),
+                (Diagnostic("Z", "Class", isSuppressed: true).WithLocation(1, 7), nameof(VsixAnalyzer))
             });
 
         // Suppressors with duplicate support for VsixAnalyzer, with 100% overlap. Verify the following:
@@ -713,15 +706,15 @@ await TestNuGetAndVsixAnalyzerCoreAsync(
             vsixAnalyzers: ImmutableArray.Create(vsixAnalyzer),
             expectedVsixAnalyzersExecuted: true,
             nugetSuppressors: ImmutableArray.Create(nugetSuppressor),
-            expectedNugetSuppressorsExecuted: FalseButShouldBeTrue,
+            expectedNugetSuppressorsExecuted: true,
             vsixSuppressors: ImmutableArray.Create(vsixSuppressor),
             expectedVsixSuppressorsExecuted: false,
             new[]
             {
                 (Diagnostic("A", "Class").WithLocation(1, 7), nameof(NuGetAnalyzer)),
-                (Diagnostic("X", "Class", isSuppressed: FalseButShouldBeTrue).WithLocation(1, 7), nameof(VsixAnalyzer)),
-                (Diagnostic("Y", "Class", isSuppressed: FalseButShouldBeTrue).WithLocation(1, 7), nameof(VsixAnalyzer)),
-                (Diagnostic("Z", "Class", isSuppressed: FalseButShouldBeTrue).WithLocation(1, 7), nameof(VsixAnalyzer))
+                (Diagnostic("X", "Class", isSuppressed: true).WithLocation(1, 7), nameof(VsixAnalyzer)),
+                (Diagnostic("Y", "Class", isSuppressed: true).WithLocation(1, 7), nameof(VsixAnalyzer)),
+                (Diagnostic("Z", "Class", isSuppressed: true).WithLocation(1, 7), nameof(VsixAnalyzer))
             });
     }
 
diff --git a/src/LanguageServer/Protocol/Features/Diagnostics/DocumentAnalysisExecutor_Helpers.cs b/src/LanguageServer/Protocol/Features/Diagnostics/DocumentAnalysisExecutor_Helpers.cs
index 12b8d9ceac862..41dade51c947f 100644
--- a/src/LanguageServer/Protocol/Features/Diagnostics/DocumentAnalysisExecutor_Helpers.cs
+++ b/src/LanguageServer/Protocol/Features/Diagnostics/DocumentAnalysisExecutor_Helpers.cs
@@ -146,6 +146,8 @@ static string GetLanguageSpecificId(string? language, string noLanguageId, strin
             // Create driver that holds onto compilation and associated analyzers
             var filteredProjectAnalyzers = projectAnalyzers.WhereAsArray(static a => !a.IsWorkspaceDiagnosticAnalyzer());
             var filteredHostAnalyzers = hostAnalyzers.WhereAsArray(static a => !a.IsWorkspaceDiagnosticAnalyzer());
+            var filteredProjectSuppressors = filteredProjectAnalyzers.WhereAsArray(static a => a is DiagnosticSuppressor);
+            filteredHostAnalyzers = filteredHostAnalyzers.AddRange(filteredProjectSuppressors);
 
             // PERF: there is no analyzers for this compilation.
             //       compilationWithAnalyzer will throw if it is created with no analyzers which is perf optimization.
diff --git a/src/LanguageServer/Protocol/Features/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.InProcOrRemoteHostAnalyzerRunner.cs b/src/LanguageServer/Protocol/Features/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.InProcOrRemoteHostAnalyzerRunner.cs
index 9523e3dd6c3d8..efc68d8751622 100644
--- a/src/LanguageServer/Protocol/Features/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.InProcOrRemoteHostAnalyzerRunner.cs
+++ b/src/LanguageServer/Protocol/Features/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.InProcOrRemoteHostAnalyzerRunner.cs
@@ -167,7 +167,9 @@ private async Task<DiagnosticAnalysisResultMap<DiagnosticAnalyzer, DiagnosticAna
 
                 if (hostAnalysisResult is not null)
                 {
-                    telemetry = telemetry.AddRange(hostAnalysisResult.AnalyzerTelemetryInfo);
+                    // Use SetItems instead of AddRange so exceptions will not occur if diagnostic suppressors are
+                    // counted in both project and host analysis results.
+                    telemetry = telemetry.SetItems(hostAnalysisResult.AnalyzerTelemetryInfo);
                 }
             }
 
diff --git a/src/Workspaces/Remote/ServiceHub/Services/DiagnosticAnalyzer/DiagnosticComputer.cs b/src/Workspaces/Remote/ServiceHub/Services/DiagnosticAnalyzer/DiagnosticComputer.cs
index 825e8bd300781..fe58571af4202 100644
--- a/src/Workspaces/Remote/ServiceHub/Services/DiagnosticAnalyzer/DiagnosticComputer.cs
+++ b/src/Workspaces/Remote/ServiceHub/Services/DiagnosticAnalyzer/DiagnosticComputer.cs
@@ -528,7 +528,15 @@ private static (ImmutableArray<DiagnosticAnalyzer> projectAnalyzers, ImmutableAr
             }
         }
 
-        return (projectBuilder.ToImmutableAndClear(), hostBuilder.ToImmutableAndClear());
+        var projectAnalyzers = projectBuilder.ToImmutableAndClear();
+
+        if (hostAnalyzerIds.Any())
+        {
+            // If any host analyzers are active, make sure to also include any project diagnostic suppressors
+            hostBuilder.AddRange(projectAnalyzers.WhereAsArray(static a => a is DiagnosticSuppressor));
+        }
+
+        return (projectAnalyzers, hostBuilder.ToImmutableAndClear());
     }
 
     private async Task<(CompilationWithAnalyzersPair? compilationWithAnalyzers, BidirectionalMap<string, DiagnosticAnalyzer> analyzerToIdMap)> GetOrCreateCompilationWithAnalyzersAsync(CancellationToken cancellationToken)
@@ -609,6 +617,7 @@ private async Task<CompilationWithAnalyzersCacheEntry> CreateCompilationWithAnal
 
             var analyzers = reference.GetAnalyzers(_project.Language);
             projectAnalyzerBuilder.AddRange(analyzers);
+            hostAnalyzerBuilder.AddRange(analyzers.WhereAsArray(static a => a is DiagnosticSuppressor));
             analyzerMapBuilder.AppendAnalyzerMap(analyzers);
         }