Thanks Martin, but not sure what circular "artifact" you're referring to.
Here is Rolf Olsen's definitive 130hr version (which was my reference when processing my own image), which also shows a bright circular region near the core.
https://www.astrobin.com/full/ylcuxo/0/
his image of course shows way more detail generally (and in the core, which if anything is brighter than what I have presented), but then he has 20x the integration that I do, and with a mono sensor