It seems the issue occurs when switching to dark mode. Please check whether an additional styling is applied to the element that displays the text in the TreeView.- I assume it is a Label. If this is not the case please open a support ticket and attach a repro project to it. Our TreeView examples in the Telerik Xamarin Samples App work as expected then the app theme/device theme is changed. You can test the demos on your side and check the demos source code.