Server configuration. Social Media uses its own LinkedIn app when SOCIAL_LINKEDIN_CLIENT_ID is set, and otherwise the sign-in app's LINKEDIN_CLIENT_ID and LINKEDIN_CLIENT_SECRET. The ID and secret always come from the same pair. The sign-in app then needs the Share on LinkedIn product and the /social-oauth/callback/linkedin redirect URL. Signing in with LinkedIn still asks only for name, email and profile.
Social Media uses the LinkedIn sign-in app by default
When SOCIAL_LINKEDIN_CLIENT_ID is empty, Social Media connects LinkedIn accounts with LINKEDIN_CLIENT_ID and LINKEDIN_CLIENT_SECRET.