Luoyang (2021)

UN is all about solving mysteries and ending conspiracies; plus finding a close bond between all characters. Both have a group of people intertwined in all of the mysteries and wanting desperately to learn the truth. Both have awesome martial arts aspects.

Investigation and mystery
the leads in both are trying to uncover the secrets of the kingdom
both are historical detective dramas

Though Tientsin Mystic is definitely a better made drama of the similar genre. Both dramas had the double male lead casting and both are also of the crime solving genre as the dramas look for what lays behind the conspiracy.