[MM-45272] Fix MM-45272 (#24701)

* Fix MM-45272

* Properly handle permalinks

* Fix

* Fix tests

* Handle only not found case for team member

* Fix lint

* Use proper config value

* Separate permission in several statements

* Add tests

* Fix lint

* Revert changes on utils

* Address feedback and more fixes

* Address feedback

* Fix test

* Fix test and related bug

* Fix and reorder test

* Address feedback

* Address feedback

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/post_metadata.go

@@ -196,7 +196,19 @@ func (a *App) sanitizePostMetadataForUserAndChannel(c request.CTX, post *model.P
 	}
 
 	if previewedChannel != nil && !a.HasPermissionToReadChannel(c, userID, previewedChannel) {
-		post.Metadata.Embeds[0].Data = nil
+		// Remove all permalink embeds and only keep non-permalink embeds.
+		// We always have only one permalink embed even if the post
+		// contains multiple permalinks.
+		var newEmbeds []*model.PostEmbed
+		for _, embed := range post.Metadata.Embeds {
+			if embed.Type != model.PostEmbedPermalink {
+				newEmbeds = append(newEmbeds, embed)
+			}
+		}
+
+		post.Metadata.Embeds = newEmbeds
+
+		post.DelProp(model.PostPropsPreviewedPost)
 	}
 
 	return post
@@ -229,6 +241,8 @@ func (a *App) SanitizePostMetadataForUser(c request.CTX, post *model.Post, userI
 		}
 
 		post.Metadata.Embeds = newEmbeds
+
+		post.DelProp(model.PostPropsPreviewedPost)
 	}
 
 	return post, nil