The person who told me I used it offensively didnt really explain why to me. I've avoided saying the word for years straight now. I still don't know how to say the word ethnic appropriately.
I can't help but think I might have said it with a colonial perspective
Btw, why is it perfectly fine here?
Off the top of my head I would define "ethnic" as a "traditional thing done by a minority group" with a focus on the minority group as an other. A workaround is simply to avoid the word and use a word like "traditional" and/or the adjective form for minority group in question.
The first paragraph with my edit
My hunch is that the article was written in Mandarin and translated. And translations can have problematic words and phrases.
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Ninja edit
Not trying to jump on you here but I think associating ethnicity only with minorities is a Western/American brainworm that reinforces "whiteness" as the default, and to an extent "superior". I feel like it connects to viewing minorities as "exotic"/other-ing them. I know you're not saying it this way and if anybody else has thoughts about this I'd love to hear them.
Ethnicity is just a group or subgroup with distinct cultural features. Nothing to do with minorities or majorities aside from how being in either group influenced their particular customs. There are majority ethnic groups and minority ethnic groups
I think you chose a bad example for this - afaik cornrows are specifically an African American thing, which would make them an ethnic hairstyle - a hairstyle specific to people of African American ethnicity. I know that your point was using it as a replacement for black is offensive, but the specific example ended up making a sentence that has its own valid meaning.