When adding widget it’s only adding widget widget-block_name but there should be theme class which is coming via register_sidebar function like here is my theme https://prnt.sc/20mvig6 have sidebar__single but in output only widget coming https://prnt.sc/20mvnyl if you then the way of monster widget of Automattic they add class of register_widget.

Please do a fix. I really appreciate this hard work.

Regards.