Description

A non-Shell TabbedPage can leak its platform renderer/manager when BarBackground is set from a shared GradientBrush, such as an app-level XAML resource used through a Style.

The platform code subscribes to GradientBrush.InvalidateGradientBrushRequested when applying TabbedPage.BarBackground, but the subscription is not removed when the TabbedPage handler/renderer disconnects. If the brush is app-lifetime, the brush keeps the old platform subscriber alive.

Observed results:

• Android: shared brush retains Microsoft.Maui.Controls.Handlers.TabbedPageManager, and the removed TabbedPage plus child page remain alive.
• iOS: shared brush retains Microsoft.Maui.Controls.Handlers.Compatibility.TabbedRenderer.
• Control path: clearing BarBackground before removal leaves zero brush subscribers and allows the captured subscriber to collect.

Steps to Reproduce

1. Clone the repro branch:

git clone https://github.com/AdamEssenmacher/maui.git
cd maui
git checkout tabbed-page-leak-repro

2. Build and run the repro project.

Android:

bash ./eng/common/dotnet.sh build src/Controls/samples/TabbedPageBarBackgroundLeakRepro/Maui.Controls.TabbedPageBarBackgroundLeakRepro.csproj -f net10.0-android -p:IncludeAndroidTargetFrameworks=true
adb install -r artifacts/bin/Maui.Controls.TabbedPageBarBackgroundLeakRepro/Debug/net10.0-android/com.microsoft.maui.repros.tabbedpagebarbackgroundleak-Signed.apk
adb shell monkey -p com.microsoft.maui.repros.tabbedpagebarbackgroundleak 1

iOS simulator:

bash ./eng/common/dotnet.sh build src/Controls/samples/TabbedPageBarBackgroundLeakRepro/Maui.Controls.TabbedPageBarBackgroundLeakRepro.csproj -f net10.0-ios -p:IncludeIosTargetFrameworks=true -p:RuntimeIdentifier=iossimulator-arm64
xcrun simctl install booted artifacts/bin/Maui.Controls.TabbedPageBarBackgroundLeakRepro/Debug/net10.0-ios/iossimulator-arm64/Maui.Controls.TabbedPageBarBackgroundLeakRepro.app
xcrun simctl launch booted com.microsoft.maui.repros.tabbedpagebarbackgroundleak

3. Wait for the repro to auto-run. It creates a TabbedPage whose app-level Style sets BarBackground from a shared LinearGradientBrush resource, replaces Window.Page, forces GC, then compares against a control path that clears BarBackground before removal.

4. Observe the result text in the app.

Expected affected result:

Leak reproduced: app resource style gradient retained the removed TabbedPage renderer/manager.

Android leak path shows:

Brush subscribers: 1
Subscriber targets: Microsoft.Maui.Controls.Handlers.TabbedPageManager
Captured subscriber target: alive
Previous child page: alive
TabbedPage: alive

iOS leak path shows:

Brush subscribers: 1
Subscriber targets: Microsoft.Maui.Controls.Handlers.Compatibility.TabbedRenderer
Captured subscriber target: alive

Control path should show:

Brush subscribers: 0
Captured subscriber target: collected

Link to public reproduction project repository

https://github.com/AdamEssenmacher/maui/tree/tabbed-page-leak-repro/src/Controls/samples/TabbedPageBarBackgroundLeakRepro

Version with bug

10.0.60

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

iOS, Android, I was not able test on other platforms

Affected platform versions

No response

Did you find any workaround?

No response

Relevant log output