This is the definitive post on the M&M fallacy (from 2014).
https://debunkingdenialism.com/2014/...ty-of-bigotry/
Why is the poisonous M&Ms analogy monstrous?
Because it can be used to prop up any kind of harmful stereotype about groups such genders, ethnicities, religious and political communities without having to engage the objections to unfair generalizations. In reality, the poisonous M&Ms analogy is a more manipulative version of the general tactic known as the “I know not all X are Y, but [flawed generalization]”. Here are some examples from the white supremacist website Stormfront: