Site Logo for external users
Site logo not shown for external users.
When you upload a site logo it will be stored in Site Assets when uploading, this library does not have "everyone" read access. If you give external users access to a specific folder in a document library they will not see the site logo.
Bad user experience. Not being able to show external anonymous users my business logo leaves them feeling like they are not at the right site. Creates customer service issues having to respond to complaints about an insecure experience.