If using Gimp 2.10 ( I hope you are ) it is worth upping the bit depth Image -> precision -> 16 bit
& linear light. screenshot: https://i.imgur.com/GLC99WJ.jpg
Then Colors -> Auto -> White Balance https://i.imgur.com/mCHRkeH.jpg
Finish off with Colors -> Hue-Saturation Adjust the hue to suit. https://i.imgur.com/oczQmkr.jpg
& linear light. screenshot: https://i.imgur.com/GLC99WJ.jpg
Then Colors -> Auto -> White Balance https://i.imgur.com/mCHRkeH.jpg
Finish off with Colors -> Hue-Saturation Adjust the hue to suit. https://i.imgur.com/oczQmkr.jpg