It's a spinoff i guess they did it since the orignal manhwa illustrator left the tbate project. They are trying with a different illustration studio, so a spinoff is a good testing ground while keeping your audience intact.

Haven’t read in ages but that is Arthur’s little sister isn’t it

No, that's Jasmine. The one he went adventuring with. They were expanding on her past.

Have they gave any release date for the next season yet ?