If media source for thumbnail info is not available for image, use the source image as a fallback. But if it is available, use it.

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesPresenter.kt

@@ -311,7 +311,7 @@ class MessagesPresenter @AssistedInject constructor(
         val textContent = messageSummaryFormatter.format(targetEvent)
         val attachmentThumbnailInfo = when (targetEvent.content) {
             is TimelineItemImageContent -> AttachmentThumbnailInfo(
-                thumbnailSource = targetEvent.content.thumbnailSource,
+                thumbnailSource = targetEvent.content.thumbnailSource ?: targetEvent.content.mediaSource,
                 textContent = targetEvent.content.body,
                 type = AttachmentThumbnailType.Image,
                 blurHash = targetEvent.content.blurhash,

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/actionlist/ActionListView.kt

@@ -260,7 +260,7 @@ private fun MessageSummary(event: TimelineItem.Event, modifier: Modifier = Modif
                 AttachmentThumbnail(
                     modifier = imageModifier,
                     info = AttachmentThumbnailInfo(
-                        thumbnailSource = event.content.mediaSource,
+                        thumbnailSource = event.content.thumbnailSource ?: event.content.mediaSource,
                         textContent = textContent,
                         type = AttachmentThumbnailType.Image,
                         blurHash = event.content.blurhash,

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/TimelineItemEventRow.kt

@@ -595,7 +595,7 @@ private fun attachmentThumbnailInfoForInReplyTo(inReplyTo: InReplyTo.Ready): Att
     val messageContent = inReplyTo.content as? MessageContent ?: return null
     return when (val type = messageContent.type) {
         is ImageMessageType -> AttachmentThumbnailInfo(
-            thumbnailSource = type.info?.thumbnailSource,
+            thumbnailSource = type.info?.thumbnailSource ?: type.source,
             textContent = messageContent.body,
             type = AttachmentThumbnailType.Image,
             blurHash = type.info?.blurhash,