Isn't this the character tagged as Kaya_(nilsunna)? Did the artist rename her or was she tagged incorrectly earlier?

It is likely the same character, in fact post #3644334 contains artist commentary referring to the character as maeryn_(nilsunna) despite it being tagged kaya_(nilsunna).

So if this post should be tagged as maeryn_(nilsunna) then post #3644334 at least should be as well based on the commentary, but I cannot say as I do not know where the name kaya_(nilsunna) came from.

It seems like the earlier works on Pixiv used Kaya, in order:

https://www.pixiv.net/en/artworks/66653359

https://www.pixiv.net/en/artworks/70351154 - post #3625434

https://www.pixiv.net/en/artworks/70318787 - post #3625427

https://www.pixiv.net/en/artworks/70318815

Then it switched to Maeryn:

https://www.pixiv.net/en/artworks/72605845 - post #3625442

https://www.pixiv.net/en/artworks/73649937 - post #3626574

https://www.pixiv.net/en/artworks/78393566 - post #3722300

Of course, one of them could be the name of the person commissioning the artwork or it could also be that the character has a first and last name?