diff --git a/lib/modules/datasource/clojure/__snapshots__/index.spec.ts.snap b/lib/modules/datasource/clojure/__snapshots__/index.spec.ts.snap
index 483eac0146289cf1f80856d6cd1fac8eaf5255e8..19b3e8b369d0335f1e4ff334d839a45fff5555bb 100644
--- a/lib/modules/datasource/clojure/__snapshots__/index.spec.ts.snap
+++ b/lib/modules/datasource/clojure/__snapshots__/index.spec.ts.snap
@@ -53,6 +53,7 @@ exports[`modules/datasource/clojure/index returns releases from custom repositor
   "display": "org.example:package",
   "group": "org.example",
   "homepage": "https://package.example.org/about",
+  "isPrivate": true,
   "name": "package",
   "packageScope": "org.example",
   "registryUrl": "https://custom.registry.renovatebot.com",
diff --git a/lib/modules/datasource/maven/__snapshots__/index.spec.ts.snap b/lib/modules/datasource/maven/__snapshots__/index.spec.ts.snap
index d6ca5371d2e48460393b9ec1c3a8ab19f341545a..6e8c05b6e8b186d42ce1ef6730b616defed9ac11 100644
--- a/lib/modules/datasource/maven/__snapshots__/index.spec.ts.snap
+++ b/lib/modules/datasource/maven/__snapshots__/index.spec.ts.snap
@@ -53,6 +53,7 @@ exports[`modules/datasource/maven/index removes authentication header after redi
   "display": "org.example:package",
   "group": "org.example",
   "homepage": "https://package.example.org/about",
+  "isPrivate": true,
   "name": "package",
   "packageScope": "org.example",
   "registryUrl": "https://frontend_for_private_s3_repository/maven2",
@@ -118,6 +119,7 @@ exports[`modules/datasource/maven/index returns releases from custom repository
   "display": "org.example:package",
   "group": "org.example",
   "homepage": "https://package.example.org/about",
+  "isPrivate": true,
   "name": "package",
   "packageScope": "org.example",
   "registryUrl": "https://custom.registry.renovatebot.com",
diff --git a/lib/modules/datasource/maven/index.spec.ts b/lib/modules/datasource/maven/index.spec.ts
index 0f818c4fa75435dc4c9882469852379a8a66e9c4..402fa00125bc3470ed878e4fd5a29008254acf2a 100644
--- a/lib/modules/datasource/maven/index.spec.ts
+++ b/lib/modules/datasource/maven/index.spec.ts
@@ -500,6 +500,7 @@ describe('modules/datasource/maven/index', () => {
         { version: '1.0.5-SNAPSHOT' },
         { version: '2.0.0' },
       ],
+      isPrivate: true,
     });
     expect(googleAuth).toHaveBeenCalledTimes(5);
   });
@@ -552,6 +553,7 @@ describe('modules/datasource/maven/index', () => {
         { version: '1.0.5-SNAPSHOT' },
         { version: '2.0.0' },
       ],
+      isPrivate: true,
     });
     expect(googleAuth).toHaveBeenCalledTimes(5);
   });
diff --git a/lib/modules/datasource/maven/index.ts b/lib/modules/datasource/maven/index.ts
index c40d7b465f634d5377520302eb60b384a10c596d..b4c4a4f54055ab3105d1ffb57f71f9726d41d23c 100644
--- a/lib/modules/datasource/maven/index.ts
+++ b/lib/modules/datasource/maven/index.ts
@@ -360,6 +360,16 @@ export class MavenDatasource extends Datasource {
         latestSuitableVersion,
       ));
 
-    return { ...dependency, ...dependencyInfo, releases };
+    const result: ReleaseResult = {
+      ...dependency,
+      ...dependencyInfo,
+      releases,
+    };
+
+    if (!this.defaultRegistryUrls.includes(registryUrl)) {
+      result.isPrivate = true;
+    }
+
+    return result;
   }
 }
diff --git a/lib/modules/datasource/maven/s3.spec.ts b/lib/modules/datasource/maven/s3.spec.ts
index f5c37a9a5b955aad5c1ea1720f1af79907f33e1c..6aed183e600a1fb3f04d811737e76f644efecf9c 100644
--- a/lib/modules/datasource/maven/s3.spec.ts
+++ b/lib/modules/datasource/maven/s3.spec.ts
@@ -91,6 +91,7 @@ describe('modules/datasource/maven/s3', () => {
           { version: '1.0.2' },
           { version: '1.0.3', releaseTimestamp: '2020-01-01T00:00:00.000Z' },
         ],
+        isPrivate: true,
       });
     });