Take my words with a grain of salt but I think this is what happened before Jujutsu Kaisen was made. Like a prototype. So I think this doesn’t really have any influence on Jujutsu Kaisen.
The curse was dispelled however, Yuuta has a massive amount of cursed energy. He can use Rika’s cursed spirit form since it has been with him for so long he knows the flow of it’s cursed energy. We cant say it is Rika chan herself but more like her cursed spirit. im not sure tho
Wait if rika's curse was dispelled then how is she stil there? In the main manga we saw rika so does it means she's still there?