Contrast issue top left corner.
That now will give you the variance as the 35mm does not exhibit this problem. It’s shot’s like this that give you the answers to the problems. Although I only adjusted the brightness and contrast yellow starts to creep in.
I have to agree with bkev. The staining is in both the 35mm and the WOWOW, but more so in the 35mm due to the higher contrast. I think the regrade shows that as well. I made a slight adjustment to remove artifacts visible for the first regrade, which includes some of the yellow staining you mentioned, but it comes out looking pretty similar:
