In the artist's X (formerly Twitter) profile, they have "絵タグ #おぷもんのえ" (lit. "Picture tag #xyz").
"おぷ" -> "Op" (first part of the artist's name)
"もん" -> "mon" - I wasn't quite sure about this one, and I could find nothing online about it. I figured it might be some type of suffix (e.g., Pokémon, Doraemon, etc.) to make it sound more "cutesy" than the artist's name alone, so I preserved it in the translation.
"のえ" seems to be the hiragana spelling for "の絵" -> "x's pictures/drawings"
Therefore, "#おぷもんのえ" -> "#Op-mon'sArt", which is their art tag.
Please let me know if this isn't right or if there's a better translation (I'm new to Japanese)!