On the low light, I don't mean when cropped I mean full frame or lightly cropped shooting in low light, I think it is redundant as I will look back at the thread I think you posted shots with high ISO in low light and that they are the same until 12,800 and then after that the R6ii is slightly better, but I don't shoot that high that often.
Don't bother trying other shots on my behalf.
Here is another severe crop the difference is the Swans were shot at 1000 ISO 1/2500 and the duck at 5000 ISO 1/2000, the full frame shot on the swans is sharper due to the lower ISO while the duck in the full frame is soft. This is the type of thing I will test as best as I can with the rental R5ii, shoot at 5000 to 12000 ISO and crop I will do that at the ponds in the early morning.
Here is the duck at a higher ISO (5000) and severe crop it looks like a painting even with AI Denoise and AI Sharpen
View attachment 11775
View attachment 11776