diff --git a/litellm/proxy/auth/auth_checks.py b/litellm/proxy/auth/auth_checks.py
index 8ade208c2b1..c4c0c43b802 100644
--- a/litellm/proxy/auth/auth_checks.py
+++ b/litellm/proxy/auth/auth_checks.py
@@ -2461,8 +2461,9 @@ async def get_team_model_aliases(
     if cached is not None:
         return _TEAM_MODEL_ALIASES_ADAPTER.validate_python(cached)
 
-    where: Final[Mapping[str, object]] = MappingProxyType({"id": model_id})
-    row: Final = await _model_aliases_table(ModelTableRepository(prisma_client)).find_unique(where=where)
+    row: Final = await _model_aliases_table(ModelTableRepository(prisma_client)).find_unique(
+        where={"id": model_id}  # mutable-ok: prisma json-serializes query args, and a mappingproxy is not serializable
+    )
     if row is None or row.model_aliases is None:
         return None
 
diff --git a/tests/test_litellm/proxy/auth/test_auth_checks.py b/tests/test_litellm/proxy/auth/test_auth_checks.py
index 109a5f3b2b3..6a63e692cdb 100644
--- a/tests/test_litellm/proxy/auth/test_auth_checks.py
+++ b/tests/test_litellm/proxy/auth/test_auth_checks.py
@@ -47,6 +47,7 @@ from litellm.proxy.auth.auth_checks import (
     _virtual_key_max_budget_check,
     _virtual_key_soft_budget_check,
     get_key_object,
+    get_team_model_aliases,
     get_team_model_aliases_for_team,
     get_user_object,
     vector_store_access_check,
@@ -1356,6 +1357,32 @@ async def test_get_team_model_aliases_for_team_guards_incomplete_context_and_del
     )
 
 
+@pytest.mark.asyncio
+async def test_get_team_model_aliases_passes_json_serializable_query_args():
+    """Prisma json-serializes query args, so a non-dict mapping makes every JWT request fail auth."""
+
+    class _JsonSerializingModelTable:
+        def __init__(self):
+            self.serialized_where = None
+
+        async def find_unique(self, *, where, include=None):
+            self.serialized_where = json.dumps(where)
+            return SimpleNamespace(model_aliases={"claude-opus-4-8": "anthropic-haiku-4-5"})
+
+    model_table = _JsonSerializingModelTable()
+    prisma_client = MagicMock()
+    prisma_client.db.litellm_modeltable = model_table
+
+    aliases = await get_team_model_aliases(
+        model_id=11,
+        prisma_client=prisma_client,
+        user_api_key_cache=UserApiKeyCache(),
+    )
+
+    assert aliases == {"claude-opus-4-8": "anthropic-haiku-4-5"}
+    assert json.loads(model_table.serialized_where) == {"id": 11}
+
+
 # Vector Store Auth Check Tests