Background flashes when Task Switcher is opened/closed during Split View

Precondition: QMainWindow with one QWidget (that supports text input) is open, e.g. QTextEdit, QPlainTextEdit, QLineEdit.

Test steps:
1. tap the QWidget text input field
--> Split View is opened
2. when the split view is visible, long press the menu key
--> Task switcher is opened and split view is visible on the background

Expected result: Background stays as it is when Task switcher is opened/closed
Actual result: Background flashes (e.g. part of the application menu is flashed) when the Task switcher is opened and closed.