One thing that got a bit lost in all of this is that "BLM" stands for two things...

1. A literal phrase that's not very controversial on its own, which many automatically agreed with and stood by.

2. An organization with its own motives and agenda, which enjoyed a period of automatic support as a side-effect.

Most of the outpouring of support was likely for the phrase, whereas much of the pushback was likely against the organization. Not sure where all of this stands now, since its left the news cycle.