According to standard FIBA interpretations, incidental contact with the shooter's hand after the ball has been released is generally not considered a foul, provided that:
The contact is light and incidental.
It does not affect the shooter's motion or ability to land safely.
It is not excessive or unnecessary.
Therefore, a defender's light "high five" to the shooter's hand after the ball has been released is typically not deemed a foul under FIBA rules.