Your canna appears to show typical symptoms of a canna virus; possible a potyvirus. The virus often interrupts the chlorophyll production in the cells. You may choose to destroy it or separate it from your other plants.
Remember that each virus produces somewhat different symptoms and they tend to change as the plant matures. Under differing growing conditions the symptoms may nearly disappear OR get progressively worse. For new growers this can be a learning experience. These plants sometimes grow and bloom to maturity, but the virus can be transmitted by sucking insects to nearby cannas. Canna viruses are not known to transmit to any other plants except other cannas.
Kent