When you select a tab the current tabpanel is not focusable (bootstrap v5).
With some screen readers (like NVDA, ORCA) you can't read the tabpanel content selected like WAI ARIA practices.
See https://www.w3.org/TR/wai-aria-practices/examples/tabs/tabs-2/tabs.html :

When the tab list contains the focus, moves focus to the next element in the tab sequence, which is the tabpanel element.