This can go both ways whether you understand both the original dub and the subtitle language that differs from the dub, for example: I recall watching a TV show episode where a conversation about a friend of theirs being drafted to war, but this piece of dialog was horribly translated: “He’s still a kid” as in the guy is his early 20s.
The subtitles in 日本語 however, used the worst wording for this idiomatic prasing by translating “kid” as in a literal minor (子供) when the real context is more on referring to someone who’s 20 years old or above (basically equivallent to saying “young man” / 若い人) which butchered the scene since the subtitles failed to express that.
I mean, do you know examples of a movie or TV show where the subtitles suck at translating the spoken dialog when it involves idioms, puns or even cultural references? Whether it’s French Dub & English Sub or vice versa (like English Dub > Spanish Sub & etc.) since each language has their own way of conveying a message.
There’s multiple ones, more prevalent with the use of ai. Like translating the ‘render’ that is an computer generated image in the meaning of plaster work.
But before that I remember a Dragonball Z episode where Gohan says to Krillin ‘lets amscray’ being pig Latin for ‘scram’, was translated like ‘to amscray’ was a verb in the DBZ universe. That’s not a big mistake, but still it stuck with me long enough to be the first example to this thread’s question.