diff --git a/ci/nightly/pipeline.template.yml b/ci/nightly/pipeline.template.yml
index ce30ab1e17f36..7b143234f3e57 100644
--- a/ci/nightly/pipeline.template.yml
+++ b/ci/nightly/pipeline.template.yml
@@ -2115,7 +2115,7 @@ steps:
         agents:
           # TODO(def-): Debezium DNS flakiness doesn't allow running on hetzner
           # queue: hetzner-aarch64-4cpu-8gb
-          queue: linux-aarch64
+          queue: linux-aarch64-medium
         sanitizer: skip
 
 
diff --git a/src/testdrive/ci/Dockerfile b/src/testdrive/ci/Dockerfile
index aa2a858291d83..af703116c8d1b 100644
--- a/src/testdrive/ci/Dockerfile
+++ b/src/testdrive/ci/Dockerfile
@@ -15,8 +15,8 @@ RUN apt-get update && TZ=UTC DEBIAN_FRONTEND=noninteractive apt-get -y install -
 COPY protobuf-bin /usr/local/bin/
 COPY protobuf-include /usr/local/include
 RUN chmod +x /usr/local/bin/protoc
-ENV PROTOC /usr/local/bin/protoc
-ENV PROTOC_INCLUDE /usr/local/include
+ENV PROTOC=/usr/local/bin/protoc
+ENV PROTOC_INCLUDE=/usr/local/include
 # Install libduckdb.so that was downloaded
 COPY duckdb-download/*/*/libduckdb.so /usr/local/lib/
 RUN ldconfig
diff --git a/test/orchestratord/mzcompose.py b/test/orchestratord/mzcompose.py
index 0cab9dbb0dc95..6e99c53fe861f 100644
--- a/test/orchestratord/mzcompose.py
+++ b/test/orchestratord/mzcompose.py
@@ -2759,20 +2759,21 @@ def helm_install_operator(
 
 
 def init(definition: dict[str, Any]) -> None:
-    try:
-        spawn.capture(
-            [
-                "kubectl",
-                "delete",
-                "namespace",
-                "materialize-environment",
-                "--wait=true",
-                "--timeout=120s",
-            ],
-            stderr=subprocess.DEVNULL,
-        )
-    except subprocess.CalledProcessError:
-        pass
+    # `--wait=true` blocks until the namespace is fully terminated. If the
+    # timeout is hit and we proceed anyway, the next `kubectl apply` races the
+    # terminating namespace and fails with "is being terminated", so let any
+    # timeout error propagate instead of swallowing it.
+    spawn.runv(
+        [
+            "kubectl",
+            "delete",
+            "namespace",
+            "materialize-environment",
+            "--ignore-not-found",
+            "--wait=true",
+            "--timeout=300s",
+        ],
+    )
     try:
         spawn.capture(
             ["helm", "uninstall", "operator", "--namespace=materialize"],