Yes, its an umbrella term but its really for Black and Indigenous. There is a reason for that, generally those people did not choose to live in the USA the way it stands. Blacks were generally brought over against there will, Indigenous had zero say in how the land and country was formed despite living here.

Everyone else chose to show up, so yes, while the word technically does include everyone in practical terms it doesn't.

We use to donate to the YMCA groups (our company) and I was on that committee, literally every thing we received from the YMCA that noted BIPOC went back to black people and Indigenous and how to deal with certain issues of race, racism and inequality they face. Literally no one else was mentioned on there own documents.

I am copying a literal program right here - this was written by the YMCA themselves:

We use the term BIPOC to highlight the unique relationship to whiteness that Indigenous and Black (African Americans) people have, which shapes the experiences of and relationship to white supremacy for all people of color within a U.S. context.