In my wallet I had a little bit over 20K BLKs.

Now I have 19,371.87 BLKs.

What happen?

In transaction I don`t see any transaction related to amount of 630 BLKs.

Please check blockchain.

https://chainz.cryptoid.info/blk/address.dws?BGDjfnnNXrzuMoDtEWh5mW2Y77ziAhQbcB.htm