Don't think this is Momiji. This is Kibisake-chan, their OC. Momiji is clearly drawn with wolf ears.
Technically, the fandom gave Momiji wolf ears, so despite Kibisake always drawing her as such, perhaps they opted to draw "canon" Momiji with an alternative costume. I admire the artist's Momiji art, but haven't looked at all of their other works so it probably is another character.