Upon first opening an image, use an Unlinked STF to see through the color cast and gradients.
PixInsight applies the same mathematical stretch to all three color channels (Red, Green, and Blue) based on the image's overall statistics. pixinsight lerar link
In the Screen Transfer Function (STF) , the button (represented by a small chain icon in the top left of the STF window) determines how PixInsight calculates an automatic stretch for your image. Upon first opening an image, use an Unlinked