I understand to some people any reminder of the south and the civil war is racist. While the reasons for the war may have been racist not all symbols had racial undertones. The confederate battle flag is one.
The Stars and bars flag had one purpose "Confederate battle flag distinct from the flag of the Confederacy, the "Stars and Bars," was created following the first major battle of the Civil War, at Bull Run near Manassas, Virginia, in July 1861, because in the heat of battle soldiers and commanders confused the Stars and Bars with the Union army's "Stars and Stripes."
https://teachinghistory.org/history-content/ask-a-historian/19424
The real answer? Its an attempt to remove the historical evidence that it was the democrats who propagated, slavery, Jim Crow, the KKK....etc., These symbols and monuments are just a reminder. Its nothing less than an act like Fascist Book Burning in order to rewrite history.