the fix

src/libraries/System.Private.CoreLib/src/System/Reflection/TypeNameResolver.cs

@@ -4,16 +4,12 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Reflection.Metadata;
-using System.Text;
 
 namespace System.Reflection.Metadata
 {
     internal struct TypeNameParseOptions
     {
         public TypeNameParseOptions() { }
-#pragma warning disable CA1822 // Mark members as static
-        // CoreLib does not enforce any limits
-        public bool IsMaxDepthExceeded(int _) => false;
         public int MaxNodes
         {
             get
@@ -22,7 +18,6 @@ public int MaxNodes
                  return 0;
             }
         }
-#pragma warning restore CA1822
     }
 }
 

src/libraries/System.Reflection.Metadata/src/System/Reflection/Metadata/TypeNameParser.cs

@@ -49,7 +49,7 @@ private TypeNameParser(ReadOnlySpan<char> name, bool throwOnError, TypeNameParse
             {
                 if (throwOnError)
                 {
-                    if (parser._parseOptions.IsMaxDepthExceeded(recursiveDepth))
+                    if (IsMaxDepthExceeded(parser._parseOptions, recursiveDepth))
                     {
                         ThrowInvalidOperation_MaxNodesExceeded(parser._parseOptions.MaxNodes);
                     }
@@ -67,13 +67,13 @@ private TypeNameParser(ReadOnlySpan<char> name, bool throwOnError, TypeNameParse
         // this method should return null instead of throwing, so the caller can get errorIndex and include it in error msg
         private TypeName? ParseNextTypeName(bool allowFullyQualifiedName, ref int recursiveDepth)
         {
-            if (!TryDive(ref recursiveDepth))
+            if (!TryDive(_parseOptions, ref recursiveDepth))
             {
                 return null;
             }
 
             List<int>? nestedNameLengths = null;
-            if (!TryGetTypeNameInfo(ref _inputString, ref nestedNameLengths, out int fullTypeNameLength))
+            if (!TryGetTypeNameInfo(_parseOptions, ref _inputString, ref nestedNameLengths, ref recursiveDepth, out int fullTypeNameLength))
             {
                 return null;
             }
@@ -154,7 +154,7 @@ private TypeNameParser(ReadOnlySpan<char> name, bool throwOnError, TypeNameParse
             // iterate over the decorators to ensure there are no illegal combinations
             while (TryParseNextDecorator(ref _inputString, out int parsedDecorator))
             {
-                if (!TryDive(ref recursiveDepth))
+                if (!TryDive(_parseOptions, ref recursiveDepth))
                 {
                     return null;
                 }
@@ -245,15 +245,5 @@ private bool TryParseAssemblyName(ref AssemblyNameInfo? assemblyName)
 
             return declaringType;
         }
-
-        private bool TryDive(ref int depth)
-        {
-            if (_parseOptions.IsMaxDepthExceeded(depth))
-            {
-                return false;
-            }
-            depth++;
-            return true;
-        }
     }
 }

src/libraries/System.Reflection.Metadata/src/System/Reflection/Metadata/TypeNameParserHelpers.cs

@@ -220,7 +220,8 @@ internal static bool IsBeginningOfGenericArgs(ref ReadOnlySpan<char> span, out b
             return false;
         }
 
-        internal static bool TryGetTypeNameInfo(ref ReadOnlySpan<char> input, ref List<int>? nestedNameLengths, out int totalLength)
+        internal static bool TryGetTypeNameInfo(TypeNameParseOptions options, ref ReadOnlySpan<char> input,
+            ref List<int>? nestedNameLengths, ref int recursiveDepth, out int totalLength)
         {
             bool isNestedType;
             totalLength = 0;
@@ -248,6 +249,11 @@ internal static bool TryGetTypeNameInfo(ref ReadOnlySpan<char> input, ref List<i
 #endif
                 if (isNestedType)
                 {
+                    if (!TryDive(options, ref recursiveDepth))
+                    {
+                        return false;
+                    }
+
                     (nestedNameLengths ??= new()).Add(length);
                     totalLength += 1; // skip the '+' sign in next search
                 }
@@ -388,5 +394,23 @@ internal static void ThrowInvalidOperation_HasToBeArrayClass()
             throw new InvalidOperationException();
 #endif
         }
+
+        internal static bool IsMaxDepthExceeded(TypeNameParseOptions options, int depth)
+#if SYSTEM_PRIVATE_CORELIB
+            // CoreLib does not enforce any limits
+            => false;
+#else
+            => depth >= options.MaxNodes;
+#endif
+
+        internal static bool TryDive(TypeNameParseOptions options, ref int depth)
+        {
+            if (IsMaxDepthExceeded(options, depth))
+            {
+                return false;
+            }
+            depth++;
+            return true;
+        }
     }
 }

src/libraries/System.Reflection.Metadata/src/System/Reflection/Metadata/TypeNameParserOptions.cs

@@ -27,7 +27,5 @@ public int MaxNodes
                 _maxNodes = value;
             }
         }
-
-        internal bool IsMaxDepthExceeded(int depth) => depth >= _maxNodes;
     }
 }

src/libraries/System.Reflection.Metadata/tests/Metadata/TypeNameParserHelpersTests.cs

@@ -122,14 +122,17 @@ public void TryGetTypeNameInfoGetsAllTheInfo(string input, bool expectedResult,
         {
             List<int>? nestedNameLengths = null;
             ReadOnlySpan<char> span = input.AsSpan();
-            bool result = TypeNameParserHelpers.TryGetTypeNameInfo(ref span, ref nestedNameLengths, out int totalLength);
+            TypeNameParseOptions options = new();
+            int recursiveDepth = 0;
+            bool result = TypeNameParserHelpers.TryGetTypeNameInfo(options, ref span, ref nestedNameLengths, ref recursiveDepth, out int totalLength);
 
             Assert.Equal(expectedResult, result);
 
             if (expectedResult)
             {
                 Assert.Equal(expectedNestedNameLengths, nestedNameLengths?.ToArray());
                 Assert.Equal(expectedTotalLength, totalLength);
+                Assert.Equal(expectedNestedNameLengths?.Length ?? 0, recursiveDepth);
             }
         }