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!

Empieza reproduciendo el comportamiento de Android TextInput con los requisitos indicados de Python, Kivy, KivyMD y buildozer.spec. Compara Kivy 2.0.0 con kivy==master y las ramas de p4a indicadas, usando la discusión enlazada como contexto. Se considera completado cuando backspace funciona y el texto introducido ya no se duplica sin requerir la versión anterior de Kivy.

Escrito por el modelo de indexación a partir del texto del issue.