I don't want to get into an argument about why an enormous border wall covering our entire southern border that mexico pays for won't fix our illegal entry problem.

As to why they built new wall? I have no idea. Maybe Biden realized he was wrong and some wall in some places helps. Maybe there was some bureaucratic reason it got built without him knowing or approving. Edit: read the article again, second reason doesn't seem likely

If you want to see democrats losing their minds over this, you won't. Most people ignore these things from their own side. Others see it but will give him a pass because this likely isn't an overall shift in strategy towards a giant wall project