I am using the WP2Social Auto Publish plugin that is configured correctly. There is also a Facebook application in which I recently added new settings with social login. I also use Cloudflare with W3 Total Cache. In my Facebook application, under "Products > Facebook Login > Settings > Valid OAuth Redirect URIs" I now have two addresses, one from WP2Social Auto Publish and the other from social login.

As in the picture, the "500 Internal Error" is displayed recently when I publish a post to Facebook for the first time. Then I have to choose "Refresh attached sharing" or use Facebook Debugger before publishing. I will also add that I have recently migrated the entire site to new hosting. My website is consolezone.pl. What can cause this error?