Observation Details
When (non-native) functionality relies on non-single pointer gestures, like swiping sliders, table columns, or opening sidebars by swipe, these must also have a single pointer variant accessible. The situation may occur, when changing to smaller viewports and the component in question is set to not use native overflow methods and to not reflow.
Users, not able to use complex pointer gestures, will not be able to access the elements in question and most likely will have difficulties to access information that is overflowing the viewport.
Remediation Notes
Ideally, elements overflowing the viewport would reflow instead. This way, the elements can rely on the user-agents functionality, and additional functionality must not be implemented. Another option would be to allow native overflow with scroll. If not using native methods to address these. If no native method is used:
Ensure, no functionality solely relies on complex pointer gestures. E.g. when using swiping functionality to navigate through slider items or table columns, ensure additionally adding accessible single pointer methods with equal functionality.
Sliders should use navigation (e.g. left/right arrow) or buttons
Responsive table columns should use navigation (e.g. left/right arrow) or buttons