diff --git a/cylc/flow/config.py b/cylc/flow/config.py
index 519dd49afc..df5d7026a8 100644
--- a/cylc/flow/config.py
+++ b/cylc/flow/config.py
@@ -2394,28 +2394,29 @@ def load_graph(self):
 
         self.set_required_outputs(task_output_opt)
 
-        # Print inferred output optionality, for debugging graph parser.
-        # Note this excludes tasks that just default to success-required.
-        optionals = [
-            f" \u2022 {name}:{output}"
-            for (name, output), (optional, _, _) in task_output_opt.items()
-            if optional
-        ]
-        requireds = [
-            f" \u2022 {name}:{output}"
-            for (name, output), (optional, _, _) in task_output_opt.items()
-            if not optional
-        ]
-        if optionals:
-            LOG.debug(
-                "Optional outputs inferred from the graph:\n"
-                f"{'\n'.join(optionals)}"
-            )
-        if requireds:
-            LOG.debug(
-                "Required outputs inferred from the graph:\n"
-                f"{'\n'.join(requireds)}"
-            )
+        if cylc.flow.flags.verbosity > 1:
+            # Print inferred output optionality for debugging the graph parser.
+            # (This does not includes tasks that default to success-required.)
+            optionals = [
+                f" \u2022 {name}:{output}"
+                for (name, output), (optional, _, _) in task_output_opt.items()
+                if optional
+            ]
+            requireds = [
+                f" \u2022 {name}:{output}"
+                for (name, output), (optional, _, _) in task_output_opt.items()
+                if not optional
+            ]
+            if optionals:
+                LOG.debug(
+                    "Optional outputs inferred from the graph:\n"
+                    f"{'\n'.join(optionals)}"
+                )
+            if requireds:
+                LOG.debug(
+                    "Required outputs inferred from the graph:\n"
+                    f"{'\n'.join(requireds)}"
+                )
 
         # Detect use of xtrigger names with '@' prefix (creates a task).
         overlap = set(self.taskdefs.keys()).intersection(
diff --git a/tests/integration/test_optional_outputs.py b/tests/integration/test_optional_outputs.py
index 4101db2456..2914a4d055 100644
--- a/tests/integration/test_optional_outputs.py
+++ b/tests/integration/test_optional_outputs.py
@@ -752,7 +752,7 @@ async def test_optional_outputs_consistency(flow, validate, graph, err):
             {
                 ("a", "succeeded"): True,  # inferred
                 ("m1", "succeeded"): True,  # default
-                ("m2", "succeeded"): False,  # inferred (override default)
+                ("m2", "succeeded"): False,  # explicit "?"
             },
         ),
         pytest.param(
@@ -802,7 +802,7 @@ async def test_optional_outputs_consistency(flow, validate, graph, err):
             """,
             {
                 ("a", "succeeded"): True,  # inferred
-                ("b", "succeeded"): False,  # inferred
+                ("b", "succeeded"): False,  # explicit "?"
                 ("c", "succeeded"): True,  # default
             },
         ),
@@ -813,7 +813,7 @@ async def test_optional_outputs_consistency(flow, validate, graph, err):
             {
                 ("a", "succeeded"): True,  # inferred
                 ("c", "succeeded"): True,  # default
-                ("c", "x"): True,  # inferred
+                ("c", "x"): True,  # explicit ":x"
             },
         ),
         pytest.param(
@@ -823,7 +823,7 @@ async def test_optional_outputs_consistency(flow, validate, graph, err):
             {
                 ("a", "succeeded"): True,  # inferred
                 ("c", "succeeded"): True,  # default
-                ("c", "x"): False,  # inferred
+                ("c", "x"): False,  # explicit ":x?"
             },
         ),
         pytest.param(
@@ -880,6 +880,7 @@ async def test_optional_outputs_inference(
             },
         }
     )
+
     config = validate(id)
     for (task, output), exp in expected.items():
         tdef = config.get_taskdef(task)
@@ -887,7 +888,7 @@ async def test_optional_outputs_inference(
         assert required == exp
 
 
-async def test_log_outputs(flow, validate, caplog):
+async def test_log_outputs(flow, validate, caplog, monkeypatch):
     """Test logging of optional and required outputs inferred from the graph.
 
     This probes output optionality inferred by the graph parser, so it does
@@ -921,6 +922,9 @@ async def test_log_outputs(flow, validate, caplog):
             }
         }
     )
+
+    monkeypatch.setattr('cylc.flow.flags.verbosity', 2)
+
     caplog.set_level(logging.DEBUG)
     validate(id)