Since the hashrate drop more than 4.5% it caused by other reason, heatwave in US is possible since they own the biggest mining farm.
The drop of hashrate should trigger more miners to join because the difficulty to mine Bitcoin is little more easier.
Hashrate drop can decrease mining difficulty but the thing is economic factors also have a role to play too it's not just a single thing that would cause everything. Imagine due to government rules and regulations a couple of mining companies or pools had to close down in certain regions or countries. Hashrate will only decrease considerably if the Hashrate they generate on the network is also considerable in comparison to the general Hashrate.