Because the protests over the summer were about police brutality. At a small number of those protests, people took advantage and rioted/looted.
The DC Insurrection was an attempt to overthrow an election by Donald Trump.
There were militia there looking to hang VP Pence from a tree. There was an armed man there who was looking to kill Speaker Pelosi. There was a guy who parked a truck with bombs near the capitol building before he attended the rally.