diff --git a/fastapi/_compat/v2.py b/fastapi/_compat/v2.py
index efc20fa58b..3245f75fef 100644
--- a/fastapi/_compat/v2.py
+++ b/fastapi/_compat/v2.py
@@ -110,10 +110,6 @@ class ModelField:
     def default(self) -> Any:
         return self.get_default()
 
-    @property
-    def type_(self) -> Any:
-        return self.field_info.annotation
-
     def __post_init__(self) -> None:
         with warnings.catch_warnings():
             # Pydantic >= 2.12.0 warns about field specific metadata that is unused
@@ -267,9 +263,9 @@ def get_definitions(
         for model in flat_serialization_models
     ]
     flat_model_fields = flat_validation_model_fields + flat_serialization_model_fields
-    input_types = {f.type_ for f in fields}
+    input_types = {f.field_info.annotation for f in fields}
     unique_flat_model_fields = {
-        f for f in flat_model_fields if f.type_ not in input_types
+        f for f in flat_model_fields if f.field_info.annotation not in input_types
     }
     inputs = [
         (
@@ -313,11 +309,11 @@ def is_scalar_sequence_field(field: ModelField) -> bool:
 
 
 def is_bytes_field(field: ModelField) -> bool:
-    return shared.is_bytes_or_nonable_bytes_annotation(field.type_)
+    return shared.is_bytes_or_nonable_bytes_annotation(field.field_info.annotation)
 
 
 def is_bytes_sequence_field(field: ModelField) -> bool:
-    return shared.is_bytes_sequence_annotation(field.type_)
+    return shared.is_bytes_sequence_annotation(field.field_info.annotation)
 
 
 def copy_field_info(*, field_info: FieldInfo, annotation: Any) -> FieldInfo:
@@ -428,7 +424,7 @@ def get_flat_models_from_annotation(
 def get_flat_models_from_field(
     field: ModelField, known_models: TypeModelSet
 ) -> TypeModelSet:
-    field_type = field.type_
+    field_type = field.field_info.annotation
     if lenient_issubclass(field_type, BaseModel):
         if field_type in known_models:
             return known_models
diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index 1e334c4296..ae89c8b6fb 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -182,8 +182,10 @@ def _get_flat_fields_from_params(fields: list[ModelField]) -> list[ModelField]:
     if not fields:
         return fields
     first_field = fields[0]
-    if len(fields) == 1 and lenient_issubclass(first_field.type_, BaseModel):
-        fields_to_extract = get_cached_model_fields(first_field.type_)
+    if len(fields) == 1 and lenient_issubclass(
+        first_field.field_info.annotation, BaseModel
+    ):
+        fields_to_extract = get_cached_model_fields(first_field.field_info.annotation)
         return fields_to_extract
     return fields
 
@@ -522,7 +524,7 @@ def analyze_param(
             assert (
                 is_scalar_field(field)
                 or is_scalar_sequence_field(field)
-                or lenient_issubclass(field.type_, BaseModel)
+                or lenient_issubclass(field.field_info.annotation, BaseModel)
             ), f"Query parameter {param_name!r} must be one of the supported types"
 
     return ParamDetails(type_annotation=type_annotation, depends=depends, field=field)
@@ -761,8 +763,10 @@ def request_params_to_args(
     fields_to_extract = fields
     single_not_embedded_field = False
     default_convert_underscores = True
-    if len(fields) == 1 and lenient_issubclass(first_field.type_, BaseModel):
-        fields_to_extract = get_cached_model_fields(first_field.type_)
+    if len(fields) == 1 and lenient_issubclass(
+        first_field.field_info.annotation, BaseModel
+    ):
+        fields_to_extract = get_cached_model_fields(first_field.field_info.annotation)
         single_not_embedded_field = True
         # If headers are in a Pydantic model, the way to disable convert_underscores
         # would be with Header(convert_underscores=False) at the Pydantic model level
@@ -866,8 +870,8 @@ def _should_embed_body_fields(fields: list[ModelField]) -> bool:
     # otherwise it has to be embedded, so that the key value pair can be extracted
     if (
         isinstance(first_field.field_info, params.Form)
-        and not lenient_issubclass(first_field.type_, BaseModel)
-        and not is_union_of_base_models(first_field.type_)
+        and not lenient_issubclass(first_field.field_info.annotation, BaseModel)
+        and not is_union_of_base_models(first_field.field_info.annotation)
     ):
         return True
     return False
@@ -936,10 +940,10 @@ async def request_body_to_args(
 
     if (
         single_not_embedded_field
-        and lenient_issubclass(first_field.type_, BaseModel)
+        and lenient_issubclass(first_field.field_info.annotation, BaseModel)
         and isinstance(received_body, FormData)
     ):
-        fields_to_extract = get_cached_model_fields(first_field.type_)
+        fields_to_extract = get_cached_model_fields(first_field.field_info.annotation)
 
     if isinstance(received_body, FormData):
         body_to_process = await _extract_form_body(fields_to_extract, received_body)
diff --git a/fastapi/openapi/utils.py b/fastapi/openapi/utils.py
index 9cff359816..0f6cf8e3af 100644
--- a/fastapi/openapi/utils.py
+++ b/fastapi/openapi/utils.py
@@ -129,7 +129,7 @@ def _get_openapi_operation_parameters(
     default_convert_underscores = True
     if len(flat_dependant.header_params) == 1:
         first_field = flat_dependant.header_params[0]
-        if lenient_issubclass(first_field.type_, BaseModel):
+        if lenient_issubclass(first_field.field_info.annotation, BaseModel):
             default_convert_underscores = getattr(
                 first_field.field_info, "convert_underscores", True
             )