you can probably use any AI generator to fix it in the same color

You haven't developed a good taste in scientific art then. The jagged mosaic edges are, IMHO, the flourish of authenticity that completes it.

Rough edges—that's like rejecting a van Gogh painting because it has too much paint and looks lumpy[0]. Art is lumpy. The ones that are perfectly flat are inkjet prints.

[0] https://en.wikipedia.org/wiki/Impasto

Btw any tip for a good printing service available in Europe if I were to mega-print this?

Here's a version with hard edges softened a bit, although my effort is a 5 min job, it scrubs up okay. Also this is a blend of visible and ultraviolet. Good old imgur, they allow massive jpeg uploads without needing to sign up or log in!

https://imgur.com/a/vRGav2d