the reason is probably because the miners are reduced
Read again. Nothing to do with miners.
This was KRAKEN delaying the transaction.
The button was clicked to send money to an address. NOTHING showed up on blockchain.info for over an hour. I only saw "0 confirmations" after about 70 or 80 minutes.
What the above users are saying OP is that they use current deposits to pay withdraws such as yours. The majority of their coins are in their cold wallet.
What the above meant was that the deposits rec'd probably didn't have 3 confirms yet and they didn't want to spend inputs they hadn't deemed as fully deposited (requiring 3 confirms).
Or simply this, the hot wallet might have run out and needed to be refilled. Any trustworthy exchange is not going to have an automatic restock of hot wallet from cold cause that risks easy hacking bankruptcy.