[BUG] app appends .bin to uncommon files uploaded

How to reproduce

1. upload an uncommon file from any android app to owncloud except owncloud. using the share function of most apps.

Expected Behavior

1. file is uploaded to owncloud retaining its extension

Actual Behavior

1. file is appended with .bin extension

Configuration Info

Latest owncloud
extension defined in both alias and mapping in config/
i can upload from any platform except android. i can also upload the file from within owncloud app fine. but if i use any android filesharing app or the app that created the file itself it gets the modified extension. it does not happen locally.

Can this problem be reproduced with the official owncloud server?
(url: https://demo.owncloud.org, user: test, password: test)
YES

### Environment data
Android version:
11
Device model:
1+ hd1925
Stock or customized system:
Stock Android 11
ownCloud app version:
latest availabe via playstore as of 10/11/21
ownCloud server version:
latest available as of 10/11/21

nextcloud had similar problem and solved by using this code
https://github.com/nextcloud/android/commit/d4aaebe5acb84c1178706aca379e2d4ca97d10bc

Start with the Android share/upload flow described in the reproduction steps and compare its handling with the linked Nextcloud Android commit. Reproduce by sharing an uncommon file from another Android app, then verify that the uploaded file retains its original extension rather than receiving .bin.