diff --git a/.evergreen/run-mongodb-oidc-test.sh b/.evergreen/run-mongodb-oidc-test.sh
index e84df2539..8ab560531 100755
--- a/.evergreen/run-mongodb-oidc-test.sh
+++ b/.evergreen/run-mongodb-oidc-test.sh
@@ -51,7 +51,6 @@ if [ -z "$PYTHON_BINARY" ]; then
 fi
 
 export TEST_AUTH_OIDC=1
-export AUTH_MECH="SCRAM-SHA-256"
 export AUTH="auth"
 export SET_XTRACE_ON=1
 bash ./.evergreen/tox.sh -m test-eg
diff --git a/pymongo/helpers.py b/pymongo/helpers.py
index 0fcd84b44..afab67e4e 100644
--- a/pymongo/helpers.py
+++ b/pymongo/helpers.py
@@ -308,6 +308,7 @@ F = TypeVar("F", bound=Callable[..., Any])
 def _handle_reauth(func: F) -> F:
     def inner(*args: Any, **kwargs: Any) -> Any:
         no_reauth = kwargs.pop("no_reauth", False)
+        from pymongo.message import _BulkWriteContext
         from pymongo.pool import Connection
 
         try:
@@ -324,7 +325,7 @@ def _handle_reauth(func: F) -> F:
                     if isinstance(arg, Connection):
                         conn = arg
                         break
-                    if hasattr(arg, "connection"):
+                    if isinstance(arg, _BulkWriteContext):
                         conn = arg.conn
                         break
                 if conn:
diff --git a/test/__init__.py b/test/__init__.py
index d025d7e08..846d4a279 100644
--- a/test/__init__.py
+++ b/test/__init__.py
@@ -95,7 +95,6 @@ TEST_LOADBALANCER = bool(os.environ.get("TEST_LOADBALANCER"))
 TEST_SERVERLESS = bool(os.environ.get("TEST_SERVERLESS"))
 SINGLE_MONGOS_LB_URI = os.environ.get("SINGLE_MONGOS_LB_URI")
 MULTI_MONGOS_LB_URI = os.environ.get("MULTI_MONGOS_LB_URI")
-AUTH_MECH = os.environ.get("AUTH_MECH")
 
 if TEST_LOADBALANCER:
     res = parse_uri(SINGLE_MONGOS_LB_URI or "")
@@ -278,8 +277,6 @@ class ClientContext:
         self.is_data_lake = False
         self.load_balancer = TEST_LOADBALANCER
         self.serverless = TEST_SERVERLESS
-        if AUTH_MECH:
-            self.default_client_options["authMechanism"] = AUTH_MECH
         if self.load_balancer or self.serverless:
             self.default_client_options["loadBalanced"] = True
         if COMPRESSORS:
@@ -347,7 +344,6 @@ class ClientContext:
 
     def _init_client(self):
         self.client = self._connect(host, port)
-
         if self.client is not None:
             # Return early when connected to dataLake as mongohoused does not
             # support the getCmdLineOpts command and is tested without TLS.