This issue occurs with some WordPress themes due to them using their own content formatting function which overrides the WordPress default function, causing some additional HTML elements to be added to the Facebook post output. If you are experiencing this issue then please try the following:
1) Enable the following setting: Facebook Feed > Customize > Misc > Misc Settings > Fix text shortening issue
2) If you’re displaying the feed in a widget then disable the setting in the widget itself that automatically adds paragraphs
3) If neither of the above fixes the issue, then try following the directions in #3 of this FAQ
If you continue to experience an issue then please contact support for further assistance.