Hiding due to the position-visibility property does not really relate more to Anchor-Based Positioning than to Anchor-Based Sizing. So it's unclear to me why the Conditional Hiding: the position-visibility property subsection logically belongs under the "Anchor-Based Positioning" section.

To my mind it would make more sense for the "Conditional Hiding" subsection to be a subsection at the end of the Overflow Management section.