I have often struggled with red objects in my 5d3. I wrote last year about it but did not get any replies. Yesterday while trying out my new 85 1.2 ii, I saw the same issue.
Red flowers come out in an over saturated red haze. The other colors seem saturated just fine, but the reds are over powered so much that the flowers lose detail.
I can reduced saturation in LR, but then the whole image looks washed out... the issue is only with reds.
If I reduce just red (Red channel only) , then it lacks punch, although I get back details in the flower...
Has anyone else observed this?
Looks like your auto white balance is thrown off by the amount of 'green' in the photo (greens look too blue). Try a WB setting of 'daylight' or 'cloudy'. I find this gives the best overall results if shooting in a 'green' environment.