diff --git a/src/sentry/api/endpoints/project_trace_item_details.py b/src/sentry/api/endpoints/project_trace_item_details.py
index b2c5363c6644cd..78dd7d8b5ced7d 100644
--- a/src/sentry/api/endpoints/project_trace_item_details.py
+++ b/src/sentry/api/endpoints/project_trace_item_details.py
@@ -170,11 +170,6 @@ def convert_rpc_attribute_to_json(
             if external_name in seen_sentry_conventions:
                 continue
             seen_sentry_conventions.add(external_name)
-        else:
-            if external_name and is_sentry_convention_replacement_attribute(
-                external_name, trace_item_type
-            ):
-                continue
 
         if trace_item_type == SupportedTraceItemType.SPANS and internal_name.startswith("sentry."):
             internal_name = internal_name.replace("sentry.", "", count=1)
diff --git a/src/sentry/search/eap/utils.py b/src/sentry/search/eap/utils.py
index 483be7ee0e277e..f6d61014606d7d 100644
--- a/src/sentry/search/eap/utils.py
+++ b/src/sentry/search/eap/utils.py
@@ -128,6 +128,17 @@ def add_start_end_conditions(
 }
 
 
+SENTRY_CONVENTIONS_REVERSE_REPLACEMENT_MAP: dict[SupportedTraceItemType, dict[str, set[str]]] = {}
+for _item_type, _replacement_map in SENTRY_CONVENTIONS_REPLACEMENT_MAPPINGS.items():
+    _internal_mapping = PUBLIC_ALIAS_TO_INTERNAL_MAPPING.get(_item_type, {})
+    _reverse: dict[str, set[str]] = {}
+    for _deprecated_alias, _replacement in _replacement_map.items():
+        _resolved = _internal_mapping.get(_deprecated_alias)
+        _internal_name = _resolved.internal_name if _resolved else _deprecated_alias
+        _reverse.setdefault(_replacement, set()).add(_internal_name)
+    SENTRY_CONVENTIONS_REVERSE_REPLACEMENT_MAP[_item_type] = _reverse
+
+
 INTERNAL_TO_SECONDARY_ALIASES: dict[SupportedTraceItemType, dict[str, set[str]]] = {
     SupportedTraceItemType.SPANS: SPAN_INTERNAL_TO_SECONDARY_ALIASES_MAPPING,
     SupportedTraceItemType.LOGS: LOGS_INTERNAL_TO_SECONDARY_ALIASES_MAPPING,
@@ -232,6 +243,12 @@ def is_sentry_convention_replacement_attribute(
     return public_alias in SENTRY_CONVENTIONS_REPLACEMENT_ATTRIBUTES.get(item_type, {})
 
 
+def get_deprecated_source_internal_names(
+    replacement: str, item_type: SupportedTraceItemType
+) -> set[str]:
+    return SENTRY_CONVENTIONS_REVERSE_REPLACEMENT_MAP.get(item_type, {}).get(replacement, set())
+
+
 def translate_to_sentry_conventions(public_alias: str, item_type: SupportedTraceItemType) -> str:
     mapping = SENTRY_CONVENTIONS_REPLACEMENT_MAPPINGS.get(item_type, {})
     return mapping.get(public_alias, public_alias)
diff --git a/tests/sentry/api/endpoints/test_project_trace_item_details.py b/tests/sentry/api/endpoints/test_project_trace_item_details.py
index add0c9809a832c..470655d767d044 100644
--- a/tests/sentry/api/endpoints/test_project_trace_item_details.py
+++ b/tests/sentry/api/endpoints/test_project_trace_item_details.py
@@ -1,3 +1,5 @@
+import pytest
+
 from sentry.api.endpoints.project_trace_item_details import convert_rpc_attribute_to_json
 from sentry.search.eap.types import SupportedTraceItemType
 
@@ -72,3 +74,57 @@ def test_convert_rpc_attribute_to_json_exposes_array_with_array_flag() -> None:
             "value": ["assistant output"],
         }
     ]
+
+
+class TestReplacementAttributeFiltering:
+    """When use_sentry_conventions is off, replacement attributes should only be
+    hidden if a deprecated source attribute is also present in the response."""
+
+    @pytest.mark.parametrize(
+        "attr_name,attr_value",
+        [
+            ("gen_ai.usage.input_tokens", {"valInt": "42"}),
+            ("gen_ai.input.messages", {"valStr": '["hello"]'}),
+            ("gen_ai.output.messages", {"valStr": '["world"]'}),
+        ],
+    )
+    def test_replacement_attribute_shown_when_no_deprecated_source(
+        self, attr_name: str, attr_value: dict[str, str]
+    ) -> None:
+        result = convert_rpc_attribute_to_json(
+            [{"name": attr_name, "value": attr_value}],
+            SupportedTraceItemType.SPANS,
+            use_sentry_conventions=False,
+        )
+
+        assert len(result) == 1
+        assert result[0]["name"] == attr_name
+
+    def test_replacement_attribute_shown_alongside_deprecated_source(self) -> None:
+        result = convert_rpc_attribute_to_json(
+            [
+                {"name": "gen_ai.usage.prompt_tokens", "value": {"valInt": "42"}},
+                {"name": "gen_ai.usage.input_tokens", "value": {"valInt": "42"}},
+            ],
+            SupportedTraceItemType.SPANS,
+            use_sentry_conventions=False,
+        )
+
+        names = [r["name"] for r in result]
+        assert "gen_ai.usage.prompt_tokens" in names
+        assert "gen_ai.usage.input_tokens" in names
+
+    def test_replacement_array_shown_when_no_deprecated_source(self) -> None:
+        result = convert_rpc_attribute_to_json(
+            [
+                {
+                    "name": "gen_ai.output.messages",
+                    "value": {"valArray": {"values": [{"valStr": "output"}]}},
+                }
+            ],
+            SupportedTraceItemType.SPANS,
+            use_sentry_conventions=False,
+        )
+
+        assert len(result) == 1
+        assert result[0]["name"] == "gen_ai.output.messages"