diff --git a/server/models/abuse/abuse.ts b/server/models/abuse/abuse.ts
index 4344df006..f85f48e86 100644
--- a/server/models/abuse/abuse.ts
+++ b/server/models/abuse/abuse.ts
@@ -563,6 +563,7 @@ export class AbuseModel extends Model<Partial<AttributesOnly<AbuseModel>>> {
     return {
       type: 'Flag' as 'Flag',
       content: this.reason,
+      mediaType: 'text/markdown',
       object,
       tag: predefinedReasons.map(r => ({
         type: 'Hashtag' as 'Hashtag',
diff --git a/server/models/video/video-comment.ts b/server/models/video/video-comment.ts
index 7f28b86b4..fa77455bc 100644
--- a/server/models/video/video-comment.ts
+++ b/server/models/video/video-comment.ts
@@ -874,7 +874,10 @@ export class VideoCommentModel extends Model<Partial<AttributesOnly<VideoComment
     return {
       type: 'Note' as 'Note',
       id: this.url,
+
       content: this.text,
+      mediaType: 'text/markdown',
+
       inReplyTo,
       updated: this.updatedAt.toISOString(),
       published: this.createdAt.toISOString(),
diff --git a/server/models/video/video-playlist.ts b/server/models/video/video-playlist.ts
index 0d43c795e..c125db3ff 100644
--- a/server/models/video/video-playlist.ts
+++ b/server/models/video/video-playlist.ts
@@ -679,6 +679,7 @@ export class VideoPlaylistModel extends Model<Partial<AttributesOnly<VideoPlayli
           type: 'Playlist' as 'Playlist',
           name: this.name,
           content: this.description,
+          mediaType: 'text/markdown' as 'text/markdown',
           uuid: this.uuid,
           published: this.createdAt.toISOString(),
           updated: this.updatedAt.toISOString(),
diff --git a/shared/models/activitypub/objects/abuse-object.ts b/shared/models/activitypub/objects/abuse-object.ts
index ad45cc064..d938b8693 100644
--- a/shared/models/activitypub/objects/abuse-object.ts
+++ b/shared/models/activitypub/objects/abuse-object.ts
@@ -2,7 +2,10 @@ import { ActivityFlagReasonObject } from './common-objects'
 
 export interface AbuseObject {
   type: 'Flag'
+
   content: string
+  mediaType: 'text/markdown'
+
   object: string | string[]
 
   tag?: ActivityFlagReasonObject[]
diff --git a/shared/models/activitypub/objects/playlist-object.ts b/shared/models/activitypub/objects/playlist-object.ts
index b561d8efd..842c03790 100644
--- a/shared/models/activitypub/objects/playlist-object.ts
+++ b/shared/models/activitypub/objects/playlist-object.ts
@@ -5,7 +5,10 @@ export interface PlaylistObject {
   type: 'Playlist'
 
   name: string
+
   content: string
+  mediaType: 'text/markdown'
+
   uuid: string
 
   totalItems: number
diff --git a/shared/models/activitypub/objects/video-comment-object.ts b/shared/models/activitypub/objects/video-comment-object.ts
index 1c058b86c..ba9001730 100644
--- a/shared/models/activitypub/objects/video-comment-object.ts
+++ b/shared/models/activitypub/objects/video-comment-object.ts
@@ -3,7 +3,10 @@ import { ActivityTagObject } from './common-objects'
 export interface VideoCommentObject {
   type: 'Note'
   id: string
+
   content: string
+  mediaType: 'text/markdown'
+
   inReplyTo: string
   published: string
   updated: string
diff --git a/shared/models/activitypub/objects/video-torrent-object.ts b/shared/models/activitypub/objects/video-torrent-object.ts
index bfbcfb1a5..9faa3bb87 100644
--- a/shared/models/activitypub/objects/video-torrent-object.ts
+++ b/shared/models/activitypub/objects/video-torrent-object.ts
@@ -33,8 +33,10 @@ export interface VideoObject {
   published: string
   originallyPublishedAt: string
   updated: string
+
   mediaType: 'text/markdown'
   content: string
+
   support: string
 
   icon: ActivityIconObject[]