Typing uppercase string into a VirtualBox guest results in gibberish

[mardukbp]

Description
Calling the type method of the Controller class with an uppercase string as argument from a Windows host with US keyboard layout results in gibberish when the active window is VirtualBox running a Windows or a Linux guest also with US keyboard layout.

Platform and pynput version
Windows 10 Home 64-bit
pynput 1.7.7

To Reproduce

Requires pywinauto.

import time
from pynput.keyboard import Controller
from pywinauto.findwindows import find_window
from win32gui import SetForegroundWindow

kb = Controller()
SetForegroundWindow(find_window(title_re='.*VirtualBox'))
time.sleep(1)
kb.type("ARROZ CON LECHE")

First run:

Second run:

The same text, but lowercase is typed correctly.

kb.type("arroz con leche")

Pressing Shift before typing and releasing it afterwards works as expected:
(#136 (comment))

kb.press(Key.shift)
kb.type("arroz con leche")
kb.release(Key.shift)

[mardukbp]

I did some more experiments. It turns out that a single uppercase letter is not typed:

kb.type("arRoz")

But two consecutive uppercase letters can have an unexpected result:

kb.type("cONfeREnce")

[mardukbp]

I performed the same experiment on Fedora with VirtualBox running Windows. Pynput types the uppercase string as lowercase!

import os
import time
from pynput.keyboard import Controller

kb = Controller()
os.system("wmctrl -a VirtualBox")
time.sleep(1)
kb.type("ARROZ CON LECHE")

For comparison, pyautogui.write correctly types the uppercase string as uppercase text into the VirtualBox window.