diff --git a/pandas/_libs/tslibs/timestamps.pyi b/pandas/_libs/tslibs/timestamps.pyi
index ecddd83322bbf..0f7800480837c 100644
--- a/pandas/_libs/tslibs/timestamps.pyi
+++ b/pandas/_libs/tslibs/timestamps.pyi
@@ -131,9 +131,17 @@ class Timestamp(datetime):
     def utcoffset(self) -> timedelta | None: ...
     def tzname(self) -> str | None: ...
     def dst(self) -> timedelta | None: ...
+    # error: Argument 1 of "__le__" is incompatible with supertype "date";
+    # supertype defines the argument type as "date"
     def __le__(self, other: datetime) -> bool: ...  # type: ignore
+    # error: Argument 1 of "__lt__" is incompatible with supertype "date";
+    # supertype defines the argument type as "date"
     def __lt__(self, other: datetime) -> bool: ...  # type: ignore
+    # error: Argument 1 of "__ge__" is incompatible with supertype "date";
+    # supertype defines the argument type as "date"
     def __ge__(self, other: datetime) -> bool: ...  # type: ignore
+    # error: Argument 1 of "__gt__" is incompatible with supertype "date";
+    # supertype defines the argument type as "date"
     def __gt__(self, other: datetime) -> bool: ...  # type: ignore
     # error: Signature of "__add__" incompatible with supertype "date"/"datetime"
     @overload  # type: ignore[override]
diff --git a/pandas/core/dtypes/base.py b/pandas/core/dtypes/base.py
index fa07b5fea5ea3..737de8a636b7d 100644
--- a/pandas/core/dtypes/base.py
+++ b/pandas/core/dtypes/base.py
@@ -480,7 +480,7 @@ def find(
                 dtype_type = type(dtype)
             else:
                 dtype_type = dtype
-            if issubclass(dtype_type, ExtensionDtype):
+            if dtype_type in self.dtypes:
                 # cast needed here as mypy doesn't know we have figured
                 # out it is an ExtensionDtype or type_t[ExtensionDtype]
                 return cast("ExtensionDtype | type_t[ExtensionDtype]", dtype)
diff --git a/pandas/core/dtypes/common.py b/pandas/core/dtypes/common.py
index 6776064342db0..802109c41567f 100644
--- a/pandas/core/dtypes/common.py
+++ b/pandas/core/dtypes/common.py
@@ -1426,7 +1426,7 @@ def is_1d_only_ea_dtype(dtype: DtypeObj | None) -> bool:
     )
 
 
-def is_extension_array_dtype(arr_or_dtype) -> bool:
+def is_extension_array_dtype(arr_or_dtype: object) -> bool:
     """
     Check if an object is a pandas extension array type.
 
@@ -1476,6 +1476,10 @@ def is_extension_array_dtype(arr_or_dtype) -> bool:
         return True
     elif isinstance(dtype, np.dtype):
         return False
+    elif isinstance(dtype, type) and issubclass(dtype, ExtensionDtype):
+        return True
+    elif not isinstance(dtype, str):
+        return False
     else:
         return registry.find(dtype) is not None
 
diff --git a/pandas/tests/arrays/test_array.py b/pandas/tests/arrays/test_array.py
index 329d28c263ff2..cb1e42258336b 100644
--- a/pandas/tests/arrays/test_array.py
+++ b/pandas/tests/arrays/test_array.py
@@ -386,6 +386,7 @@ def registry_without_decimal():
 def test_array_not_registered(registry_without_decimal):
     # check we aren't on it
     assert registry.find("decimal") is None
+    assert registry.find(DecimalDtype) is None
     data = [decimal.Decimal("1"), decimal.Decimal("2")]
 
     result = pd.array(data, dtype=DecimalDtype)