Love of Thousand Years (2020)

Both are historical dramas centered around the revenge plot by the FL who, after being betrayed and losing everyone she loves, returns for revenge through a fantasy twist (face swap vs. time travel).

Both dramas are historical and are about the FL who, after being betrayed and losing those she loves, has her face exchanged with another girl. She then returns for revenge. Both MLs have been in love with the FLs for a long time, something the FLs are unaware of.

Both FLs have their faces exchanged with another girl and are believed to be dead, and both are on a quest (to solve a mystery vs. revenge). Both MLs are mysterious figures who the FL initially doubts.

Both dramas involve a FL whose country/family was destroyed by the villain. She returns through a supernatural means (time travel vs. face swap/new identity) for revenge. Both couples have a love-hate relationship from the FL's side.

The actress are both a princess and goes into another setting where she becomes a servant to the male lead. The male lead is an immortal and falls in love with the female lead after undergoing tragic experiences.

Both drama have: soul-body swapping, martial arts, intrigues, plots, battles and in general they share a similar atmosphere.

Both Female lead have a bit similar story about Come back with different face and identity to revenge