TikTok bots frown upon uploaded videos with watermarks. If you attempt to upload such videos, you may get blocked with a message notifying you that your action is against the terms of the app. Secondly, the song might be the problem if your upload was blocked even without a watermark. Some artists do not permit the unauthorized use of their songs on TikTok. Also, most users use specific apps to edit their videos before uploading them to TikTok. As a result, some of them may have hidden watermarks that may trigger the bots on the platform.