Hello @tama-music,
Unfortunately, you are indeed correct. There have been many cases where ill-intentioned people have registered music that wasn’t theirs. This is a very bad situation that can become a nightmare to sort out. Some of the very top authors have fallen victim to these scams.
Registering your music yourself, is the only way to make sure it won’t be claim by someone else.
I can only encourage you to protect your music. However, currently AdRev and most other third-parties affiliated with ContentID no longer accept music author from royalty-free platform such as AudioJungle. So when you sign up do not present yourself as an Audiojungle or otherwise “royalty-free” author. Or else, they will reject your application, which would be very unfortunate.
All the best!