In the flow inside the main screen of the mobile app, the OpenInExternalBrowser action is called several times to browse to a web page to download documents. Its working correctly in iOS but in Android, only allows to call one time and you have to close the app to browser to the web page using the OpenInExternalBrowser action.
Based on my observation on android, after triggering OpenInExternalBrowser, it will only stick to using only one tab even after triggering it multiple times unless you redirect to another domain on the browser. Only then it will open a new tab. Other than that behavior it works fine.
What web page are you opening using the OpenInExternalBrowser? Also, what is the default browser on your mobile?
Is a web app with a pdf viewer to show and allow the user to download the pdf.