I’m one of very few on IIS who don’t use the popular and traditional Astro software like PS , PI to process their deep space images.
I use Startools which is a totally different animal ( active signal evolution tracking) but does a superb job at Star correction and Star reduction . There are a few modules which can either dampen down your Star field or directly reduce Star size and brightness.
https://www.startools.org/modules/repair
https://www.startools.org/modules/magic
Unfortunately due to Startools being an active tracking process it’s best to use it autonomously from start to finish. If you just use it for one or two modules and continue in another software like PI , then you loose its signal to noise tracking capabilities. It can be done but not recommended
Cheers
Martin