I saw @Lisa Stranger post the earliest "rumors" (minimally substantiated facts) of this recently. This morning I finally saw "Credible" (well-substantiated) sources getting on the story, like the embedded podcast and the attached web page below.
The linked webpage below has embedded video that was initially live-streamed showing early on that it WAS NOT the protesters causing damage. The #UmbrellaMan does seem like a cop and his only alibi is other police who were all dressed in murky black clothing amidst the chaos.
Still, the best story to read is that linked webpage at the bottom of my microblog post here. They discuss Right-wing extremists and #accelerationists in the latter half. That's some sick stuff festering in our society.