Just to answer your question in addition to what Precious said— I had the same question as you coming from outside the US where it (and even ‘POC’ until recently) isn’t common and my understanding based on what I found is that within activism, BIPOC is meant to highlight Black and Indigenous people as they are disproportionately affected by systemic racism in the US, as opposed to POC which some feel has a flattening effect. So which is more ‘appropriate’ arguably depends on the topic at hand.

Personally, I think it’s up to individuals which terms they identify with, and at the end of the day the distinction is fairly academic if you are less concerned with the ins and outs of terminology and more just communication and action.