There are a few places in base Plone where links are given the hiddenStructure class. They are off screen but not display:none, and affect tab order. One example is plone.app.layout/plone/app/layout/viewlets/searchbox.pt at master · plone/plone.app.layout · GitHub. At my org, an internal accessibility review flagged these links as violating WCAG 2.4.3 Understanding Success Criterion 2.4.3 | Understanding WCAG 2.0
I'm not an accessibility expert, can someone on the Plone team explain why these are there? It looks like maybe they were put here for accessibility reasons, or perhaps they are outdated and mistakenly left in during the BS5 update?