That extra chapter is probably something that happened in the novel but never got introduced in the manhua afterall the vibe of the story is like when she was still travelling together with Lord Hell and his two underlings and she clearly says: "You shrank again?" so it happened more than once during their travels, but was probably something that the authors of the manhua thought as irrelevant to the main story so they left it out, but now for some reason they put one part of that extra story in, which made the series feel wierd, but if you read the travel arc then you can place this in the there IMO and it will work fine, uness there's another travel arc somewhere in the future? Didn't read the novel so dunno...