At Ethereum block height 13,773,000 the network will implement the Arrow Glacier upgrade which aims to postpone Ethereum’s Difficulty Bomb.
The Arrow Glacier network upgrade will go into effect around 10 December, delaying the “difficulty bomb”, an increase in mining difficulty, until June 2022 as the blockchain transitions from proof-of-work (PoW) mining to PoS.
The Difficulty Bomb was supposed to happen 4,000,000 blocks or 611 days after the Muir Glacier network upgrade. However, Arrow Glacier will push the bomb back further to June 2022. This will give ethereum PoW miners another six months to continue mining the Ethereum blockchain until the June 2022 change. Once the Difficulty Bomb does happen the mining difficulty will make it so PoW miners get phased out because it will be too difficult.