Privacy Browser Android

This is actually the behavior of the Android file picker when saving a file with the same name as an existing file.

For privacy and security reasons Privacy Browser does not have permissions to access the file system directly. Instead, when saving a file the user is kicked out to Android's file picker, which handles the actual writing of the file to the file system. This prevents the security scenario where a malicious website is able to compromise Privacy Browser and prevents such a malicious site from being able to read or write files without the user giving explicit permission each time through the standard Android file picker.

The file picker provides the opportunity for the user to choose a different name for the file, but it doesn't provide any visual indication that there is a conflict. If the user does not select a new name it appends (1), (2), etc. to the file name to make it unique. Because this is appended after the file name extension it messes with auto detection of the file type.

As this is a bug with a standard Android element that affects a whole bunch of apps, Privacy Browser isn't really the place to fix it. There is always the chance that Google might modify this behavior in future versions of Android of their own accord. And you are always welcome to submit a bug report to Google about the issue at https://issuetracker.google.com/. Often Google just ignores bug reports, but every once in a while you are able to get through to someone.