this is pretty normal since Ha is the strongest signal and gets mapped to the G channel.
if you unlink the channels in STF you might see something a little less green.
probably a good way to go about this is to use the old color calibration tools - first find the background area and use the largest value as the tolerance in BackgroundNeutralization. actually set it slightly higher.
then you can use ColorCalibration - turn off structure detection for the white balance, and turn on "output white reference mask". look at the background values in the image again (they will have changed) and set the white lower limit just above that value. for the background reference you can set the upper limit to the same value.
now run CC and undo/redo while fiddling with the white lower limit until you see only the nebula in the white reference mask. when that looks good then the colors should be a tad more balanced.
at this point sometimes i do SCNR to green at 100%. sometimes not, depending on how it looks. then follow this flow to get the SHO colors right:
My first attempt at a script and my first time programming in JavaScript so please excuse any newbie errors. Any feedback on non-idiomatic PJSR programming, bugs or improvements will be gratefully received. The ColorMask script is intended to provide a convenient and interactive method for...
pixinsight.com
you can also just use the unlinked STF copied to HT instead of all the color balancing stuff, that is certainly a strategy. but if you want to use MaskedStretch or ArcsinHStretch you need to get the colors balanced in the linear stage.
with GHS you can do a per-channel stretch so you might be able to get the colors looking less green from within that script.
rob