One of the interesting problems of every public service is that the amount of possible states a given user can land in grows exponentially over time. In many cases the easiest way to reproduce the situation is log in as this user. However it goes against privacy considerations of course. On dabdab private notes should be treated as private by developers as well.
An approach one could take is to allow to impersonate a user and fake all the content of the user while keeping the structure. If a user has a stream with three records, one of which has a youtube embed and the other has a list in it, generating some stream with the fake content which would have one message with embed and another one with a list should be enough for troubleshooting while keeping user data private.