Moving files from one folder to another in Lightroom Classic

It's probably my own idiosyncrasies. Buut I find that the drag/drop method can be a little precarious, and I sometimes drop the images in the wrong folder and then spend time trying to find where they went. Another way to move images is to highlight the images that you want to move and then right-click on the folder that you want to move them to and choose the option to move the images to that folder. Personally, I find that method to be a little more reliable for me.

In Library Folders panel, select your 2019 folder then the 2012 photos within same. Drag the selected photos to the 2012 folder.