If it opens the browser and does not redirect, it's likely an issue with your hosted URL, not on the device. Make sure your hosted URL has the correct association and link files for Android and iOS; this is what tells the device browsers to loop for apps and redirect them from the website.

Here are the Flutter docs with a video on how to implement deep linking

Steps:

1. Make sure your app files and permissions are correctly set up for android for iOS
2. Ensure your hosted URL has the correct assetlint.json and apple-app-site-association files for Android and iOS, respectively. You can see how to configure those files in the Flutter deep linking tutorial video.