As people have noted multiple times, AMD drivers 20.4.2 and lower don't have near the performance issue. Seems like this issue was introduced in driver 20.5.1 of which they did make a change related to D2: "When performing a task switch, Destiny™2 may experience an application hang or black screen." Everyone please continue submitting tickets to AMD via their "AMD Bug Report Tool" after each update of your driver. We need this issue to look large to them (and it actually is) by giving them a large number of submissions. This will increase the likelihood this could be resolved in the next driver update.