i think the use of BLM (or the template X Lives Matter) being for only black issues) is based on many things, but the main issues seem to be that BLM is primarily about black people being murdered by the state (although its also been stretched to address all of black struggle), which is not what is happening to asian people right now.

BLM or X Lives Matter being a template for only blacks is also partially based on the reasoning that black issues, black struggle, black thought and AAVE are often co-opted by every other race, while every other race is still incredibly anti black, causing people to be a little more protective over the phrase. X lives matter has been so co-opted by everyone to the point that all lives matter or white lives matter is a far right rallying cry and now "x lives matter" is now one of the first things that often gets brought up and debated when BLM is discussed

It doesnt help that other groups fighting for equality lately have literally used the X lives matter template to racistly play oppression olympic games / showing that their care for black people and black issues are conditional

i understand that stuff like blue lives matter is already bastardizing the BLM phrase and movement in a way asian lives matter never could, but that doesnt mean non black X lives matter isnt without its problems that are specific to black people's relations with other minority races aside from white supremacy (altho its all white supremacy at the end of the day) //like at some protest in support of the right wing backed harvard suit for anti asian bias an east asian dude was holding up a sign saying "my life matters too" shit is cringy, disrespectful and contributes to black distrust