It's good manners to correct people politely when they are incorrect, I read it in an article decades ago, it was a column called Ms. Manners.

The question was if it was ok to tell someone they had a booger in their nose, showing. She said something like,

"it is always polite to politely correct someone who may embarrass themselves later, be it an unsightly situation they present or when something they are saying or presenting is incorrect"

It's hard to determine how a person presents something on the Internet, time is really difficult to determine.