System Information
Operating system: iOS, Mojave, 10.14.6
Graphics card: Radeon Pro Vega 56 8 GB

Blender Version
Broken: 2.90, 2020-08-31, as found on the splash screen)
Worked: 2.83

Short description of error
There are two bugs

1. permanent crush in Cycle mode, after activating Denoising Data in Passes, and adding Denoiser Node in Compositing window, after making a render Blender crashes every time. Without Denoiser it's OK.
2. Activating Denoising options in Render Properties and changing shading into Cycles in viewport crushes Blender every time.

Exact steps for others to reproduce the error
As above