QTabWidget: background application comes visible on Split view after changing focus between text widgets

Preconditions:

Application includes QTabWidget. Tab includes many QSpinBoxes (tested with 4 spin boxes) on the tab screen area. SpinBoxes are located at top, bottom and center of the tab screen area, vertically centered.
Application is on portrait mode.

Test steps:
1. Tap the QSpinBox at the bottom of tab screen.
--> split view is opened and the focus is on tapped QSpinBox.
2. Tap the QSpinBox above.
--> focus is changed to tapped QSpinBox.
3. Tap the QSpinBox above.
--> focus is changed to tapped QSpinBox.
4. Tap the QSpinBox above.

Expected result:
Focus is changed to tapped QSpinBox.

Actual result:
Focus is changed to tapped QSpinBox. Background application is visible between the status pane and split view screen area.