How should a Headless UI popover group behave when tabbing?

[airblade]

The docs for grouping related popovers say:

This [the popover group] ensures panels stay open while users are tabbing between Popovers within a group, but closes any open panel once the user tabs outside of the group

The focus management docs say:

Pressing Tab on an open panel will focus the first focusable element within the panel's contents. If a PopoverGroup is being used, Tab cycles from the end of an open panel's content to the next Popover's button.

The keyboard interaction docs for Tab say:

Tabbing out of an open panel will close that panel, and tabbing from one open panel to a sibling Popover's button (within a PopoverGroup) closes the first panel

I'm confused about what happens when you tab out of a popover which is in a group. Should its panel remain open or should it close?

Also, I still don't really understand when you would use a popover group. What are they for? I couldn't find any examples of a popover group online to see its behaviour in the wild.

Thank you in advance!