diff --git a/mypy/checker.py b/mypy/checker.py
index 5d97a0dec713..a21780defe0c 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -5305,9 +5305,7 @@ def conditional_types_for_iterable(
                 for key in item_str_literals:
                     if key in possible_iterable_type.required_keys:
                         if_types.append(possible_iterable_type)
-                    elif (
-                        key in possible_iterable_type.items or not possible_iterable_type.is_final
-                    ):
+                    elif key in possible_iterable_type.items:
                         if_types.append(possible_iterable_type)
                         else_types.append(possible_iterable_type)
                     else:
diff --git a/test-data/unit/check-typeddict.test b/test-data/unit/check-typeddict.test
index 7de8e6416f35..c57f34ce2f7e 100644
--- a/test-data/unit/check-typeddict.test
+++ b/test-data/unit/check-typeddict.test
@@ -2017,9 +2017,7 @@ v = {bad2: 2}  # E: Missing key "num" for TypedDict "Value" \
 [case testOperatorContainsNarrowsTypedDicts_unionWithList]
 from __future__ import annotations
 from typing import assert_type, TypedDict, Union
-from typing_extensions import final
 
-@final
 class D(TypedDict):
     foo: int
 
@@ -2037,20 +2035,16 @@ else:
 [typing fixtures/typing-typeddict.pyi]
 
 [case testOperatorContainsNarrowsTypedDicts_total]
+# flags: --warn-unreachable
 from __future__ import annotations
 from typing import assert_type, Literal, TypedDict, TypeVar, Union
-from typing_extensions import final
 
-@final
 class D1(TypedDict):
     foo: int
 
-
-@final
 class D2(TypedDict):
     bar: int
 
-
 d: D1 | D2
 
 if 'foo' in d:
@@ -2058,6 +2052,11 @@ if 'foo' in d:
 else:
     assert_type(d, D2)
 
+if 'unknown_key' in d:
+    object()  # E: Statement is unreachable
+else:
+    assert_type(d, Union[D1, D2])
+
 foo_or_bar: Literal['foo', 'bar']
 if foo_or_bar in d:
     assert_type(d, Union[D1, D2])
@@ -2083,69 +2082,20 @@ def f(arg: TD) -> None:
     else:
         assert_type(arg['bar'], int)
 
-
 [builtins fixtures/dict.pyi]
 [typing fixtures/typing-typeddict.pyi]
 
-[case testOperatorContainsNarrowsTypedDicts_final]
+[case testOperatorContainsNarrowsTypedDicts_totalFalse]
 # flags: --warn-unreachable
 from __future__ import annotations
-from typing import assert_type, TypedDict, Union
-from typing_extensions import final
-
-@final
-class DFinal(TypedDict):
-    foo: int
-
-
-class DNotFinal(TypedDict):
-    bar: int
-
-
-d_not_final: DNotFinal
-
-if 'bar' in d_not_final:
-    assert_type(d_not_final, DNotFinal)
-else:
-    spam = 'ham'  # E: Statement is unreachable
-
-if 'spam' in d_not_final:
-    assert_type(d_not_final, DNotFinal)
-else:
-    assert_type(d_not_final, DNotFinal)
-
-d_final: DFinal
-
-if 'spam' in d_final:
-    spam = 'ham'  # E: Statement is unreachable
-else:
-    assert_type(d_final, DFinal)
-
-d_union: DFinal | DNotFinal
-
-if 'foo' in d_union:
-    assert_type(d_union, Union[DFinal, DNotFinal])
-else:
-    assert_type(d_union, DNotFinal)
-
-[builtins fixtures/dict.pyi]
-[typing fixtures/typing-typeddict.pyi]
-
-[case testOperatorContainsNarrowsTypedDicts_partialThroughTotalFalse]
-from __future__ import annotations
 from typing import assert_type, Literal, TypedDict, Union
-from typing_extensions import final
 
-@final
 class DTotal(TypedDict):
     required_key: int
 
-
-@final
 class DNotTotal(TypedDict, total=False):
     optional_key: int
 
-
 d: DTotal | DNotTotal
 
 if 'required_key' in d:
@@ -2158,6 +2108,11 @@ if 'optional_key' in d:
 else:
     assert_type(d, Union[DTotal, DNotTotal])
 
+if 'unknown_key' in d:
+    object()  # E: Statement is unreachable
+else:
+    assert_type(d, Union[DTotal, DNotTotal])
+
 key: Literal['optional_key', 'required_key']
 if key in d:
     assert_type(d, Union[DTotal, DNotTotal])
@@ -2167,23 +2122,19 @@ else:
 [builtins fixtures/dict.pyi]
 [typing fixtures/typing-typeddict.pyi]
 
-[case testOperatorContainsNarrowsTypedDicts_partialThroughNotRequired]
+[case testOperatorContainsNarrowsTypedDicts_NotRequired]
+# flags: --warn-unreachable
 from __future__ import annotations
 from typing import assert_type, Required, NotRequired, TypedDict, Union
-from typing_extensions import final
 
-@final
 class D1(TypedDict):
     required_key: Required[int]
     optional_key: NotRequired[int]
 
-
-@final
 class D2(TypedDict):
     abc: int
     xyz: int
 
-
 d: D1 | D2
 
 if 'required_key' in d:
@@ -2196,6 +2147,11 @@ if 'optional_key' in d:
 else:
     assert_type(d, Union[D1, D2])
 
+if 'unknown_key' in d:
+    object()  # E: Statement is unreachable
+else:
+    assert_type(d, Union[D1, D2])
+
 [builtins fixtures/dict.pyi]
 [typing fixtures/typing-typeddict.pyi]