What is the reason for the android virtual keyboard bug with .htpasswd authorization in the application?

Question

Android

If the web application uses authorization via .htpasswd , then on mobile devices (Android 6 in my case) there is an unpleasant bug with all INPUT DOM elements, namely, it is impossible to enter any characters other than numbers.
To reproduce the bug, you will need to:
1.) password-protect the local page with any string inputs
2.) access this page from a real mobile device (cannot be played through browserstac)
3.) enter the login password .htpasswd
4.) focus on the input and try to enter any symbols from the virtual keyboard
Here is a detailed video of this bug: youtube
The result will be that it is possible to enter only numbers, letters and symbols of any layout are ignored.
Is this a browser bug or an OS bug?
PS If you open a new tab where you no longer need to enter a login password, then everything works fine.