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When this policy is active, a frame or main page content will not be able prevent its content from scrolling vertically. This is done by:

• Ensuring all scroll related input events (e.g. touchstart) are non-cancelable.
• Treat touch-action: none as if it were touch-action: pan-y). Meaning the page still blocks pan-x and zoom.
• Ensuring programmatic scrolling using the DOM scroll APIs is handled within the scope of the frame, i.e., calls to el.scrollIntoView() do not propagate outside of the frame.
• Ensuring that no scrollable layer is targeted for scroll gestures (to avoid a frame from consuming all the scroll gestures).

The frame below uses body{ touch-action: none; } to prevent its content from scrolling. However, when the policy is "on", it will be scrollable!. In other words, the policy prevents the page from blocking vertical scroll by treating the touch-action: none as touch-action: pan-y.

Try scrolling the iframe below on mobile (e.g. using touch events).