What you are missing is that at least half the White and Black support for BLM was from people who thought it was a cool slogan and who thought having a BLM top on would signal how woke they were. Over the summer, kids out of school and frustrated at the Covid lockdowns got to hang out and do a little rioting at BLM demonstrations. Sure they called themselves allies or whatever else you wanted them to call themselves. Then there came a point where people really started to get tired of the looting and the violence. Many people began to see BLM was more than a trending slogan. It was actually a movement that was not so nice. It was trashing shops and trying to defund the police and bothering people in diners. Then kids realized you could get arrested and your career prospects would go down the tube. Suddenly it was time to go back to school, even if it was mostly on-line. BLM had become stale and tedious and preachy- no one wants to keep hearing that overblown rant. No one ever believed in that systemic racism thing anyway: they were upset over the George Floyd video. Goodbye BLM and on to the next thing.