My .NET version is 528372, which means .NET 4.8. As a professional .NET Software Engineer I highly doublt an update to the latest 4.8.1 will have any effect. There are so many .NET applications out there running Windows Forms or WPF frontends on .NET 4.8. If you read the official release notes it is highly unlikely that there will be any improvement on the current matter. And if the .NET runtime had any rendering issues on AMD graphics cards, the Microsoft forums would already explode.
I do not know the internal processing structure of Affinity Photo, but crashing a display driver is usually caused by direct unsafe rendering calls via the graphics API. What does Affinity use in Windows? DirectX, OpenGL or Vulkan? I am sure it is Metal for MacOS, right? Since all crashes on my end have to do with transformations, adjustments, layers, cropping and such, my guess is that Affinity delegates those tasks directly to the GPU for acceleration and somehow manages to tear it down.
Also, I am open to help in any way possible. Meaning running debug builds for logging and such. I really want V2 to work... I mean... I kinda paid for it