@RawConvert Interesting. Useful site. I compared the 80D with the D7500. Not much difference but I’d guess Canon are saving higher iso for later or decided not worth doing.
The flattening you have posted on the 6DII might have something to do with fake low iso settings. It might be worth looking at noise performance as well if that isn’t included in the graph.
Off topic but also looked at 80D compared with an OMD E-M5 and E-M1. As I own both I know that the E-M5 is better on noise, not much though but I have used it to take test shots at ISO 25,600. I’d say that there was more range than 3 stops in the shot if that is what the vertical axis is. Ok needed noise reduction and not suitable for all shots due to that. On the other hand maybe there was only 3 stop range.
Lucky me. I bought the 80D and not for dynamic range.