please ignore initial repro project and use TestReadback.zip attached later
somewhere deep inside LWRP we decide to use this format for metal - this does not make this issue metal specific

Steps to reproduce:
1. open TestReadback scene and press play

Actual Result:
there may/will be asserts and errors. The most important part is that script attached to camera shows texture copy of RT - they will be very different (to make sure script make sense you can tweak it to use "saner" format)

please note that you can freely ignore ValidateFormat error if that happens - it is simply logged (not an exception) and it happens because c#-side SystemInfo.IsFormatSupported is very weird

THE reason:
on all platforms AsyncReadback reads data from texture as is and then use ImageReference to do on-CPU conversion. ImageReference works strictly with TextureFormat and not all GraphicsFormat/RenderTextureFormat can be mapped to TextureFormat

please note that repro uses GraphicsFormat.B10G11R11_UFloatPack32 but it will be reproduced with RenderTextureFormat.RGB111110Float

hence i removed regression flag but i keep "first affected version" as i didnt bother to check that way back