LinkedIn locked me out of my own account. The only way back is through Persona — a third-party service that wants a photo of my passport, a scan of my face, and a recording of my movements (liveness detection: turn your head, follow the dot, so a still photo can’t stand in for me). The stated reason: “unusual activity.” The real reason, of course, is big tech spearheading a movement toward absolute control over people.
They accept written/scanned proof of identity signed by a municipal office (german here). Basically, show your ID to an official and haven them sign a paper to proof your identity. Also, a friend told me, a LinkedIn Support Member may neither have capacity nor skill to validate a foreign documents authenticity.