The difficulty setting decreases if the cost of mining bitcoin is negative, so that the remaining miners continue mining. It can never reach 90% because the balance would be achieved much earlier
The top of the 2020 red zone is going to go down
I answer comparing it 2020 with 2016, If the price does not rise, in the next 30 days, it adjusts for time, with the adjustment of difficulty and remains below the price which will continue to rise.

It is an indicator and as everyone can have their flaws but it helps us to see things from another point of view.