Assuming some group is able to afford depositing bricks all over the country at convenient places for rioters, shouldn't we also assume that another group might exist that is able to hire a few twitter accounts to post pictures of pallets of bricks?
Don't get me wrong, I have no idea if one or the other is right, but wouldn't the latter be cheaper and easier to do?

Also I have some suspicions about this one:
https://twitter.com/Conserv17716651/status/1267458034273484808

Obviously it might have been terribly interesting to see what is written on the packing slip (things like a recipient, shipping company or manufacturer or maybe a date proving it is from now etc.), I wonder why that good american citizen taking this photo didn't think of that. At least I am hopeful this was all reported to the police first, before taking it to twitter.