You see Schumers office referenced and immediately jump to him making it up. That's weird. Here's a fox article on it. The original I read was interviewing the poor people who cleaned it. Yes it's an opinion piece but that this happened is not disputed.
https://www.foxnews.com/opinion/jan-6-under-the-capitol-dome-the-darkest-entry-yet-in-clios-tablet
Marauders roamed the Capitol. Trashed the Senate parliamentarian’s Office. Wielded Confederate flags in the Ohio Clock Corridor outside the Senate chamber. Ripped down the nameplate to the entrance of the office suite of House Speaker Nancy Pelosi, D-Calif. Vandalized a statue of President Zachary Taylor. Carved "Murder the Media" in a Capitol doorway. Extremists defecated in the hallways, stomped in their own feces and tracked their excrement across the encaustic, Minton tiles.