How do I read the history of my reputation?
My reputation score has gone down, but the reputation tab in my profile does not indicate why. Is this a bug? What else could have caused it?
Unexplained changes in reputation are often reported when deletion is involved. Such changes are hidden by default, but it is possible to see them by enabling the "show removed posts" option on the bottom of your profile's reputation tab.
There are two main types of deletion for the purpose of this post:
Note that this can also apply to unexplained increases in reputation if a deleted user had downvoted you, or you had downvoted an answer that was later deleted.
Without looking at the details of your account, we can't be sure that you're not seeing a reputation calculation bug. However, moderators are the only people who can see those details, and bugs have rarely if ever been at fault in the past.