It is a tradition that old ASICs need to plug out instead of making negative profits. Here ASICs are getting old based on its profitability. So, the recent reward-drop made lots of miners old just after the day of halving. The entire mining industry needs to cope with new block-rewards and profitability, definitely it will take some time; because, out of competition some miners may even continue with negative profits with the expectation of reaching profits with future prices rather than opting to quit. Small miners are the first ones to quit or switch over to higher hash power. So, it will take time that bitcoin mining to get back to profitable after halving.

For the same reason, bitcoin prices do find a dump immediately followed by the halving but this time bitcoin markets managed to sustain at same levels to slight higher prices probably thanks to 100x more transaction fees. Usually higher transaction fees lead to bull markets. This way, when bitcoin markets remain in bullish mode, we can expect mining difficulty to increase.