This is one of the very few BG's with JPG artifacts where noise reduction only helped so much. To push it further would clean up more of the artifacts, but would also lose precious detail.
This is all pretty much due to the "pointillist" artistic stippling of dots, as seen in the figure.
Some of the yellow levels need a boost, and there's a lot of obvious reflections in the mirrored portions that need to be removed. Image is 100% JPG, so no data loss. [unskewed, image processed, de-yellowed, sharpened]
You can interact with the ChatGPT Bot in any Chat Room and there is a dedicated room. The command is /ai followed by a space and then your ? or inquiry.
ie: /ai What is a EM Pinball Machine?