prevent image preview to default view when adding/removing reaction (#6910)

webapp/components/post_view/post_body_additional_content.jsx

@@ -55,11 +55,13 @@ export default class PostBodyAdditionalContent extends React.PureComponent {
     }
 
     componentWillReceiveProps(nextProps) {
+        if (nextProps.previewCollapsed !== this.props.previewCollapsed || nextProps.post.message !== this.props.post.message) {
             this.setState({
                 embedVisible: nextProps.previewCollapsed.startsWith('false'),
                 link: Utils.extractFirstLink(nextProps.post.message)
             });
         }
+    }
 
     toggleEmbedVisibility() {
         this.setState((prevState) => {