I think many people were complaining about PTD being sung in an English language and not Korean while never criticising them for releasing Japanese music. Might be that?
Yeah I've discussed this before on here, quite recently too about the why the reactions are different, although it wasn't related to fetishisation.
You can still fetishise Asians if they sing in a non-Asian language, I don't think that has stopped anyone before.
Didn't stop Oli
They could sing a Spanish song, and it wouldn't decrease the "fetishisation level" they're under. I think people would go harder for them singing in Spanish than in Japanese, and by people I mean I-fans (possibly western fans that she is referencing?) There are I-fans that speak Spanish too, obviously, but their language isn't as dominant globally as English and so it wouldn't be seen as counter hegemonic.
Tbh Asians singing and speaking English with an Asian accent can be like a kink for some people.