Definition of the extended analogy fallacy
The fallacy of the Extended Analogy often occurs when some suggested general rule is being argued over. The fallacy is to assume that mentioning two different situations, in an argument about a general rule, constitutes a claim that those situations are analogous to each other.
Every time an analogy is used it is used to state that A is similar to B in a particular way. It does not (necessarily) insinuate that they are alike in any other way. However, often opponents will attempt to attribute your use of the analogy to extend it to something not analogous as proof of your lack of logic.
Here's real example from an online debate about anti-cryptography
"The slaughter of billions of
chickens each year is morally wrong. Like the Nazi holocaust."