I don't think the protests were actually popular among every single liberal, but it was considered taboo to say anything against them. I lost several friends during this period, expressing my concerns about the protests, and more specifically the organization behind them. I was called an Uncle Tom.
My former workplace hired outside therapists to attend to us people of color, and held special town halls and discussions. Meanwhile, I was losing sleep because the local strip mall was being looted, and I had to listen to gu shots all night. I spent one night sleeping on the floor of my living room with my guns due to reports of break-ins in my neighborhood.
I'll totally agree that it was a bit of a taboo to speak badly of the protests in some circles, but the enthusiasm for the whole thing quietly died among many people for exactly the reasons you describe.
That was the messsage being blasted at max volume by CNN, NYT, WaPo, and the rest. They were outraged when the capitol police responded to far left insurrectionists setting the national mall on fire. So yes, it is safe to say that was a mainstream viewpoint.