I've just read the fixed bugs release notes but I think they have changes since than as for LinkedIn there is no more Marketing Developer Platform in the product section and the permissions are different.
The only thing for Facebook that I found is "Ensure that your app has the 'pages_manage_posts', 'pages_read_user_content' and 'read_insights' permissions, upgrade the Facebook API Version to 'v8.0', and generate a new page access token for your Facebook app in Kentico." which I don't know or dont see in the Facebook module to update these permissions nor in the Settings > Security and Membership > Authentication > Facebook.
Nevertheless, the problem occurs when clicking Authorize on the Facebook module and Select a company in the Linkedin module where it says that the domain isn't added or just breaks.
In the facebook app configuration I added all domains and checked them with the Redirect URI validator tool that is right below the allowed domains, but it still doesn't work and the Linkedin after selecting a company just redirects to the "Bummer" error with my website link.
Any other ideas on why this is behaving like this ?