diff --git a/kokoro/linux/python310_cpp/continuous.cfg b/kokoro/linux/python310_cpp/continuous.cfg
index 1f91c26713..e76abe18a0 100644
--- a/kokoro/linux/python310_cpp/continuous.cfg
+++ b/kokoro/linux/python310_cpp/continuous.cfg
@@ -11,7 +11,9 @@ env_vars {
 
 env_vars {
   key: "BAZEL_TARGETS"
-  value: "//python/... @upb//python/..."
+  # Note: upb tests don't work since the C++ extension takes precedence here.
+  # Note: upb tests don't work since the C++ extension takes precedence here.
+  value: "//python/..."
 }
 
 env_vars {
diff --git a/kokoro/linux/python310_cpp/presubmit.cfg b/kokoro/linux/python310_cpp/presubmit.cfg
index 1c4cfeebc8..5b87fd6c51 100644
--- a/kokoro/linux/python310_cpp/presubmit.cfg
+++ b/kokoro/linux/python310_cpp/presubmit.cfg
@@ -11,6 +11,7 @@ env_vars {
 
 env_vars {
   key: "BAZEL_TARGETS"
+  # Note: upb tests don't work since the C++ extension takes precedence here.
   value: "//python/..."
 }
 
diff --git a/kokoro/linux/python37_cpp/continuous.cfg b/kokoro/linux/python37_cpp/continuous.cfg
index 44f6606a9f..ebef92806f 100644
--- a/kokoro/linux/python37_cpp/continuous.cfg
+++ b/kokoro/linux/python37_cpp/continuous.cfg
@@ -11,7 +11,8 @@ env_vars {
 
 env_vars {
   key: "BAZEL_TARGETS"
-  value: "//python/... @upb//python/..."
+  # Note: upb tests don't work since the C++ extension takes precedence here.
+  value: "//python/..."
 }
 
 env_vars {
diff --git a/kokoro/linux/python37_cpp/presubmit.cfg b/kokoro/linux/python37_cpp/presubmit.cfg
index 54b2de47e1..ebef92806f 100644
--- a/kokoro/linux/python37_cpp/presubmit.cfg
+++ b/kokoro/linux/python37_cpp/presubmit.cfg
@@ -11,6 +11,7 @@ env_vars {
 
 env_vars {
   key: "BAZEL_TARGETS"
+  # Note: upb tests don't work since the C++ extension takes precedence here.
   value: "//python/..."
 }
 
diff --git a/kokoro/linux/python38_cpp/continuous.cfg b/kokoro/linux/python38_cpp/continuous.cfg
index dc24fd2a3d..decd466494 100644
--- a/kokoro/linux/python38_cpp/continuous.cfg
+++ b/kokoro/linux/python38_cpp/continuous.cfg
@@ -11,7 +11,8 @@ env_vars {
 
 env_vars {
   key: "BAZEL_TARGETS"
-  value: "//python/... @upb//python/..."
+  # Note: upb tests don't work since the C++ extension takes precedence here.
+  value: "//python/..."
 }
 
 env_vars {
diff --git a/kokoro/linux/python38_cpp/presubmit.cfg b/kokoro/linux/python38_cpp/presubmit.cfg
index f9d025a3af..decd466494 100644
--- a/kokoro/linux/python38_cpp/presubmit.cfg
+++ b/kokoro/linux/python38_cpp/presubmit.cfg
@@ -11,6 +11,7 @@ env_vars {
 
 env_vars {
   key: "BAZEL_TARGETS"
+  # Note: upb tests don't work since the C++ extension takes precedence here.
   value: "//python/..."
 }
 
diff --git a/kokoro/linux/python39_cpp/continuous.cfg b/kokoro/linux/python39_cpp/continuous.cfg
index f11d73ed89..97970087b0 100644
--- a/kokoro/linux/python39_cpp/continuous.cfg
+++ b/kokoro/linux/python39_cpp/continuous.cfg
@@ -11,7 +11,8 @@ env_vars {
 
 env_vars {
   key: "BAZEL_TARGETS"
-  value: "//python/... @upb//python/..."
+  # Note: upb tests don't work since the C++ extension takes precedence here.
+  value: "//python/..."
 }
 
 env_vars {
diff --git a/kokoro/linux/python39_cpp/presubmit.cfg b/kokoro/linux/python39_cpp/presubmit.cfg
index d7deef5b69..97970087b0 100644
--- a/kokoro/linux/python39_cpp/presubmit.cfg
+++ b/kokoro/linux/python39_cpp/presubmit.cfg
@@ -11,6 +11,7 @@ env_vars {
 
 env_vars {
   key: "BAZEL_TARGETS"
+  # Note: upb tests don't work since the C++ extension takes precedence here.
   value: "//python/..."
 }