Try to show full image as the fallback of the thumbnail.

vector/src/main/java/im/vector/riotx/features/media/ImageContentRenderer.kt

@@ -127,6 +127,23 @@ class ImageContentRenderer @Inject constructor(private val activeSessionHolder:
             GlideApp
                     .with(imageView)
                     .load(resolvedUrl)
+                    .listener(object : RequestListener<Drawable> {
+                        override fun onResourceReady(resource: Drawable?, model: Any?, target: Target<Drawable>?, dataSource: DataSource?, isFirstResource: Boolean): Boolean {
+                            return false
+                        }
+
+                        override fun onLoadFailed(e: GlideException?, model: Any?, target: Target<Drawable>?, isFirstResource: Boolean): Boolean {
+                            data.url
+                                    ?.takeIf { it != resolvedUrl }
+                                    ?.let {
+                                        GlideApp
+                                                .with(imageView)
+                                                .load(it)
+                                        return false
+                                    }
+                            return true
+                        }
+                    })
         }
     }