This question is an exact duplicate of:
I've been noticing a weird behaviour in the past couple of days, that I thought I should report. When someone deletes an answer I had downvoted, the reputation tab highlights all the reputation I got that day, instead of just the +1 it should show. Has anyone else noticed this?
Before deletion of downvoted answer:
Some time later, one of the downvoted answers is deleted:
The tab should read +1, but it displays +19 instead. This didn't happen before.