How old is Mona in Genshin Impact?

Could you tell me, if you happen to know, what is the age of Mona in the popular game Genshin Impact? Her mysterious persona and her skills in astrology have piqued the curiosity of many players, but her exact age remains somewhat of a mystery. Have there been any hints or clues in the game's lore or character stories that might give us a clue about how old Mona truly is?