Krishna paintings with a flute do not hold a negative influence. However, there are few myths revolving the same:
It is said that ghosts can start living in the flute.
Also, boys can get addicted to flute. This could not be acceptable in few Indian families.
Girls can be inspired by Mira and refuse to live a married life.
However, there is no negative influence in going for radha krishna paintings with a flute as it is auspicious in every way. Krishna is a God of love. Thus, anything done with love will be accepted by him.