I don't really know too much about this but apparently he calls himself an astrophotographer and not an astronomer, so maybe the use of photoshop isn't all that surprising.

https://www.bbcearth.com/news/extreme-night-sky-with-bray-fa...

his images on consumer hardware have smaller details than the hubble or meter wide telescopes on the ground. he says it's his processing skill, but it's probably really because he (at some stage of the process) puts his images through topaz denoise which invents detail.