About a month ago, I posted a question on MSE. It got 3 upvotes and no downvotes, but today I lost 4 reputation for that question. The question is linked below:
Thanks in Advance!
You lost a total of $4$ reputation because each downvote costs you $-2$ rep (there were two), and the times at which they were cast can be viewed in your profile. A place showing more details about your post can be found in this timeline.
However, you have asked a good question so I don't understand those downvotes. For your interest, here is a meta post concerning proof-verification questions.