hi nadine! :) i’ve read the novel so i can tell you what actually happened in the ending —no need to wait for season 2, as it most likely won’t focus on the main leads but their child instead.
so jin mi was reborn in the mortal world, but she “cultivated” to become an immortal —or as the citizens in the ending were gossiping about, a “demon” (we must remember that xu feng is still part of the demon realm even though he has given liu ying the demon ruler position).
the reason why jin mi remembers xu feng after being reborn it’s because she has passed her “love trial”. in the drama, Lord Duomu said “If your heart lives, your fate will not end. Ashes of brahma is protecting her —she sacrificed herself in the heaven and demon realm battle and saved the six realms from suffering, it’s the highest merit and virtue. Her trial has been undone. She’s waiting for you at where you two first fell in love.” The place where xu feng “snatched the bride” was where they first met when they were living in the mortal realm. And obviously, the ashes of brahma did protect her, hence why the drama title is ashes of love.
this together, makes jin mi still jin mi after being reborn. how do we know this? it’s quite evident when she said that she can still not see colours while xu feng was playing with their child :)
next, how do we know she is immortal? i guess it requires basic knowledge about this whole xianxia concept but i don’t mind explaining :) to put it simple, a human can “cultivate” to become an immortal. this was exactly what jin mi did. she was reborn as a mortal, but she cultivated to become an immortal. it’s a lot easier for her too, especially after when xu feng “snatched the bride”; he has prepared 6000 years of prowess for her. in the novel, it makes it more obvious that the prowess is one of the things that is symbolic of them expressing their love for each other because jin mi will ask for it every day. take note that in the drama, she was obsessed with asking for prowess in the early episodes, so for xu feng to give her the 6000 years of prowess not only helps with her cultivation and immortality but this is also seen as a replacement of her dowry and an answer of his love for her :) we know she is immortal because no mortal can cope with 6000 years of prowess without cultivating.
as for the question about them living in the mortal realm in the ending, yes this is true in the drama (however, in the novel they remained in the demon realm). in the drama, while xu feng was searching for jin mi’s spirit he resided at the house that she resided at in the mortal realm when they were having their redemption. we can assume that this is the house they’re now living in the mortal realm to live a peaceful life as xu feng has given up the position as demon king. since the beginning, he has only cared about jin mi anyways so it doesn’t matter to him where they’re living. but one thing we know for sure, he still doesn’t want to be part of the heaven realm; it’s an interesting aspect of this story because the good and bad are twisted in the heaven and demon realm —quite realistic i say because people usually fantasise heaven being the place where peace is everything but in actual fact, everything and everywhere has flaws.
but of course, this doesn’t mean that they stopped communicating to other people in the other realms. for example, jin mi is still nurturing flowers, evidently when lian qiao from the flower realm came to the demon realm to gift liu ying the “iris” saying that it was a new flower nurtured by the water immortal; jin mi is the water immortal, another reason to believe that she is still an immortal after being reborn. in the novel, she visits the moon/fox immortal a lot and tends to get in trouble by xu feng for always hanging around with the moon/fox immortal :’)
answering johanna — their child is not half mortal, half immortal. he is a full immortal. it’s more obvious in the novel, but in the drama we know this because jin mi calls her son xiao lu (remember that his real name is tang yue, which is a name given by xu feng because tang yue was the name of the family shop that jin mi was reborn at. in the novel, jin mi calls xu feng lazy because of this lmao). xiao lu basically means “little lu” and the “lu” in his name comes from his real form which is a white egret (the result of a phoenix + a frost flower). this is why he is dressed in white! white egret in chinese is called “bai lu” :)
i highly recommend for you guys to read the novel (it’s translated by online fans!). It’s pretty short too, so it’s not going to waste your time haha :’) the epilogues makes the story so much more satisfying! It’ll be interesting to see what the production team has in store for season 2, because there is no “season 2” in the novel lmao. i personally think the ending was perfect in season 1 so i’m highly anticipating for the second season! :)
i hope this reply answers your questions!