Sort:  

No. Editing the post was not the reason for the $500 to $0 change. A whale apparently changed his upvote to a downvote.

But why did he do it ? How to find him and ask this?

The screenshot is from steemstats.com. Enter your user name. Click on Votes to see who voted on your posts/replies.

When I can see that? What is it?

Coin Marketplace

STEEM 0.14
TRX 0.22
JST 0.031
BTC 79049.07
ETH 2101.22
USDT 1.00
SBD 0.64