Given European peoples’ hair darkens and lightens to varying degrees (sun bleaching, bleaching hair with honey or citric juice), as much as the semantics and words for dirty blond/light brown varies I have the feeling that those with dirty blond/light brown hair are one of the lucky ones in that their hair didn’t darken much.
(Curious why almost nobody calls it wine blond, given it doesn’t darken that badly.)
If I’m not mistaken, a good number of people do colour their hair a different colour and since that colour seems somewhere in the middle and can even appear kind of dull (to some), that I recall a forum with users talking about how and why such a hair colour gets a bad rap.
Right down to the unkind names. (Westerners do have a similar dilemma regarding their natural hair, not just with the wavy hair but also with the dark blond/light brown hair thing.) Though I highly suspect these might be pretty common in Germanic and Slavic speaking countries.
(Spain and Portugal might not be exempt though.) So far only Russian, French and Italian languages, to my knowledge, have a specific word to describe light brown/dark blond hair. It’s not necessarily that odd as I think a good number of Europeans do have that hair colour.
But it’s also highly stigmatised to the point where whilst some do dye it another colour, others keep it as it is. (Though it may be that they’re either more daring or more accepting of themselves or whatever.)