I’ve been hearing from people I know who have been participating in nighttime protests/property protection that social media posts on Snapchat/Facebook/reddit are disappearing or seeing significant posting delays. I can’t confirm it personally, but the social media chatter last night was significantly lower than previous nights (though - to be fair - the Minneapolis streets did start clearing out around 11-12).

How often does that occur in police misconduct incidences?

It's usually because of fear of police retribution.

In a large scale protest, surveillance and military drones are the end game IMO.