I think there are two basic reasons:
There’s a lag between infection and test, between test and hospitalization, and between hospitalization and death. So death is the chart that will go up the latest, and there are a lot of long-tail deaths from people who were infected a long time ago, so death rate rises are less “spikey” than infections.
Case fatality rate has trended down in general. Hospitalization-death rate has roughly halfed since the first wave.
Scientists aren’t entirely sure why 2. is happening, but there are multiple possible explanations, all of which probably contribute to some degree.
In some places, many particularly vulnerable people are already dead.
The average age of newly infected people has gone down after the first spike, probably for multiple different reasons, including older people being more careful on average. Also, we might be getting slightly better at protecting vulnerable populations. Younger people have a much higher chance of surviving an infection.
Mask wearing decreases the initial viral load that triggers an infection, which causes a less severe, more survivable infection.
Treatments are getting more effective.
Perhaps also higher availability of testing and higher awareness means more people with mild symptoms get tested?
More people with mild symptoms getting tested sounds like a cause. I buy that.
Awareness is a good guess but the July hump also had high awareness.
The lag was not previously two weeks. I doubt the lag got longer so I suspect there is a real and large CFR reduction.
The four lower points sound plausible and are some good news, finally :)