in the Accessibility Features section of this example it states:

Note that since the first element in every tabpanel is a focusable element (i.e., a link), the tabpanel is not included in the page Tab sequence. To make it easy for screen reader users to navigate from a tab to the beginning of content in the active tabpanel, it is recommended that all tabpanel elements in a tab set are focusable if there are any panels in the set that contain content where the first element in the panel is not focusable.

This seems to me to be a very unusual set up for an example - I would suggest it's not very likely that, in a real-world Tabs interaction, the first element in every tab panel would be a link.

It might, therefore, make for a better example if you were to change this so that:

• the example doesn't have a link as the first element in each panel
• the example gets updated to show how to handle that (far more common) setup, and:
• the explanatory note updated to mention that you don't need to set the tab panel elements as focusable when you know for sure that the first element in each tab panel is focusable?