I'm white, so I should not be taken as an authority on how this applies to BIPOC folks, but...

All marginalized groups have differences of opinion within them, and very strong ones, about the means of their liberation. They have direct experience with the subject matter, but that doesn't necessarily make every single one of them right - just as working class people who voted for Trump are not necessarily right to think he'd end their economic struggle. I believe both that:

1. members of a marginalized group should be the authority on how to treat that group, and their voice should be heard and taken seriously regardless of whether they are criticizing or upholding the actions of allies, and
2. members of the relatively privileged group who wish to be allies still can and must use critical thinking about how to support the marginalized, rather than just taking the first marginalized person they hear at face value and assuming it represents everyone.

I think, based on what I have heard, that whether it's okay to use symbols from other cultures strongly depends on context, intent, and the consent of the culture you are pulling from.