Kivy App on Android keyboard/TextInput doesn't work properly: backspace has no effect and input doubles randomly

Python == 3.9.1
kivy == 2.1.0.dev0
KivyMD == 0.104.2.dev0

Here are the requirements from buildozer.spec:
requirements = python3,kivy==master,https://github.com/kivymd/KivyMD/archive/master.zip,sdl2_ttf==2.0.15,requests,urllib3,chardet,idna,android,plyer,jnius,pillow

The keyboard doesn't work properly with TextInput fields. Backspace doesn't work at all, and the already inputed text just doubles at random, e.g. by typing 'qwerty123' you would get 'qwerty123qwerty123'. (And you can't delete it, because backspace doesn't work).

The bug is very similar to what is described [here](https://groups.google.com/g/kivy-users/c/ZuHsbOjcmwU), although the proposed solution doesn't work in my case.

IMPORTANT:

In buildozer.spec I'm specifying 'p4a.branch == develop'. Because with the default 'p4a.branch == master' the app crashes on Android when you just focus on a TextInput.
This bug does not appear when using kivy == 2.0.0. BUT using kivy == 2.0.0 is not an option because it lags extensively on Android.

Thanks in advance!

まず、記載されている Python、Kivy、KivyMD、buildozer.spec の要件で Android TextInput の動作を再現します。リンクされたディスカッションをコンテキストとして使用し、Kivy 2.0.0 と kivy==master、および報告されている p4a ブランチを比較します。古い Kivy バージョンを必要とせずに backspace が機能し、入力したテキストが重複しなくなれば完了です。

索引モデルが issue の本文から書いたものです。