In general we must try to assume good faith. These mistakes, although they seem really obvious to you, they may not be deliberate. It may be someone who thinks that they know what they are doing.
I would try to ask the person more about what they are interested in, and what they like to look at, and whether they need help understanding iNat, rather than just asking them to stop, which could seem rude or confrontational, however gently you say it.
And if it is a child or a trouble-maker/troll doing this deliberately, trying to make friends with the person may help cause them to give up doing this.