Image link Firebase Realtime-Database - Firebase App Check token is invalid

Question

I saved an image in firebase storage and a link to it in the firebase realtime database. So far everything worked great. Recently I've been getting the error message "Firebase App Check token is invalid" when I access the link. Not for all images, just for some. If I copy the link into the web browser, this is what is displayed:

{
  "error": {
    "code": 401,
    "message": "Firebase App Check token is invalid."
  }
}

I created the images from an emulator with app-check debug token, could that be the problem?