You don't need to pre-zoom your art for PJ, because PJ has zoom buttons that let viewers choose how big to view the piece. If your whole piece fits as the preview image, you don't need to upload a detail file at all.
Even images that you think look better zoomed in are better uploaded at 1x, and you can mention your preferred zoom in the description. That way viewers have the freedom to see it how they want, but can also see it how you like it.
I don't know if this is one of the articles you read, but it's a great reference: link
I located two good examples of things to avoid in your picture, using terminology from the above link: link_2
Thank you for commenting on this! You mean below the eyes for example (and shading in general)? I'm a beginner and I just read some articles on banding, but It's possible I didn't quite catch the concept entirely.
That's one sad frog. Also, this piece has issues with banding.
Thank you for the advice! Unfortunately, I'm not able to remove the detail image I already posted - but I'll keep it in mind for future posts.