Adele has done nothing wrong. I think she looks great sporting the look she's sporting.
She's not 'appropriating' anything, she's endorsing it, appreciating it, and living it. She's not undermining your culture, she's propagating it; something you ought to be happy about.
I love it when non-Punjabi people show up at our family events in a sari or a sherwani, and hey - a turban! And they've made the effort to pick up some Bhangra steps - I love them for it!
No one has ever pulled me up for jazzing up the scene in a double-breasted blazer and worsted trousers, or a tie, or a shirt with collars and cufflinks, a necktie or bow I can tie in 15 seconds without a mirror. Hell, I pull off the 007-esque, privately educated posh kid look with lazy ease! (Heehee! That's because I am a privately educated posh kid, and lazy ease is my thing - but that's besides the point).
In the picture below I see an amazing songstress, a vocal powerhouse that I have admired for years, a little girl just a tad older than my boy, announcing her victory of a personal battle with her weight.
And you see what?