Alright, so I went through a few of the xmps posted above and … I don’t understand them. At all!
First of all, I went through the settings posted by @sovereign; the process that removed the blue color cast is a single channel mixer with destination red and settings R+0.95 G-0.1 B0. Ok, if I replicate this on my original photo I get weird yellowish colors. I understand this may be due to the different white balance settings, but what I don’t see is how did he get to that point. There’s nothing intuitive here! Is there a reasoning behind? Did you fix the white balance first or what? How did you get to those parameters in the channel mixer?
Second issue, there was a discussion on input profiles above. I may be missing something but what is the problem with input profiles? The defaults are input=standard color matrix, working=linear rec 2020 rgb. Should they be changed? Why @gaaned92 made that comment about “too much tuning for defective input profile”? why defective? How defective? how can you tell it’s defective? Picture me with a big question mark and a dumb expression on my face.
Third, color zones as used by @yteaot. Finally, a single module that I can probably use it, no problems! … well turns out that I have problems also on this!!! I see how it’s been used (by dropping a big hole in the saturation panel right where the blues are) but again – I’m unable to draw that sharp rectangle .