By Medha Singh and Lisa Pauline Mattackal (Reuters) – Bitcoin miners are feeling the heat – and the pain’s rippling downstream to pressure prices. The cryptocurrency’s spectacular rally in 2021 drew thousands of entrants into mining, or producing new coin. As a result the hashrate, or combined computational power used by bitcoin miners globally, has roughly quadrupled over the past six months to blow past 200 million “terahashes” per second. But what’s that got to do with the price of bitcoin? A rising hashrate makes it becomes harder for miners to earn coin and cover their costs of hardware, …