Basically, there was a bug where a user tried to power down and it resulted in a negative balance. This prevented all steem witnesses from producing blocks as they were all halted on a particular one.
The good thing is that no accounts or tokens were in danger and it also seems like it hasn't affected the price of Steem in the markets.
Yeah fortunately it doesn't affected the nice raising price :)
And thanks a lot for your detailed and interesting answer my friend !