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.
Tons, I know tons. Some of them even get into the cultural zeitgeist as jokes. For example in Final Fantasy VII they translated “Your party is waiting for you on the second floor” as “Su fiesta le espera en el pisos 2” (if you don’t understand Spanish, they translated party/group as party/celebration)