It's not a surprise for anyone since Bitcoin's halving on May 11 a lot of things have changed concerning the mining. As you all know the reward for a mined block was divided by two and as a result the miners who earned the least decide to give up. This big wave of departures brings down the hashrate of the all network, in continuity the mining difficulty is adjusted in order to compensate.
If I wanted to talk about this phenomenon it's because 3 days ago, on June 4 the mining difficulty of Bitcoin dropped twice.. in a row. That event is pretty rare so let's go deeper into it and let's see how this will evolve in the future.
1. What really happened ?
Like I previously said the mass exodus of the least profitable miners resulted in a huge drop for the hashrate, in order to correct it adjustments are being made. Every 2016 blocks to be more precise, these adjustments are based on the hashrate involved in its consensus by proof of work. Although the halving doesn't yet have real effects on the Bitcoin's value it did, however, hurt the "small miners" who left, as a consequence on May 20 the hashrate registered a drop of 6%.
And even more unprecedented the hashrate dropped a second time by 9.3% on June 4. A reduction of the hashrate raises some questions especially concerning Bitcoin's strength, in a way it could make Bitcoin weaker : less hashrate means that the cost of a 51% attack would be lower. Even if some people are pessimistic, a lot more are optimistic and are convinced that in comparison to the accumulated hashrate this decrease won't affect Bitcoin under any circumstances.
2. What can we expect in the future :
It has been a while since we witnessed a drop like this, even during the crash on March 12 the hashrate hadn't decreased in this way. As we speaking the mining difficulty is around 13.73 T, and in conjunction the hashrate is 98.3 EH per second. This situation is not unprecedented because a "double drop" like this one regarding the mining difficulty happened 7 times in the past, it could help us to predict what will come next.
Concerning the future, some experts think that the halving effect hasn't yet been fully felt, and we could witness a third drop of the hashrate during the up-coming weeks, which will even rarer. The last time it happened was actually 2 years ago and it had a major impact on Bitcoin's price which dropped to $3.500, if a similar situation happens it wouldn't be surprising to see Bitcoin's value fall.
We will see what the future stores for us but it could be a serious obstacle for Bitcoin ascent and will destroy all the progress made in recent times. Bitcoin will have to break trough many resistances in order to comeback, however we can also expect a more positive outcome, more and more people agree that Bitcoin could manage to reach $20.000 by the end of 2020.