QTabWidget: extra menu comes visible & background application flashes while changing focus between text widgets on split view

Preconditions:

Application includes QTabWidget. Tab includes many text widgets: QTextEdit, QPlainTextEdit, QComboBox, QLineEdit. They are vertically centered.
Application is on portrait mode.

Test steps:
1. Tap the QLineEdit.
--> split view is opened and QLineEdit is focused. Qwerty keyboard is open.
2. Tap the QSpinBox above.
3. Tap the QPlainTextEdit above.

Actual result:

• After setp 2: Focus is changed to tapped QSpinBox. Background application flashes when the virtual keyboard layout is changed from qwerty to alphanumeric.
• After step 3: background application flashes shortly and then some extra menu comes visible with items like: Undo Ctrl+Z, Redo Ctrl+Y, Cut Ctrl + X etc. Press Cancel button --> Split view is visible again, QPlainTextEdit has focus. Extra lines are visible on status pane (note: there's separate error for that use case).