Which church was told, "You have abandoned your first love"?

Answer: Ephesus

Jesus praised Ephesus for its labor and perseverance, but rebuked it for abandoning its first love.

““To the angel of the church in Ephesus write: These are the words of Him who holds the seven stars in His right hand and walks among the seven golden lampstands.”— Revelation 2:1 (BSB)