First of all i'd like to know what this is about:
I think this is a very insufficient info. In my opinion there should be some exceptions for each of these issues:
1- A user that you answered one of his/her question was removed.
2- A user that answered your question was removed.
3- A user that commented on your question was removed.
4- A user that upvoted one of your questions was removed.
5- A user that upvoted one of your answers was removed.
6- A user that upvoted one of your comments was removed.
and some other that can cause any rep changes.
Or at least there can be a better explanation such as "A user that up/down voted some of your questions/answers/comments was removed!"