Mending barely works in snapshot 20w49a

People have been having problems with mending, but this is different. In the latest snapshot, 20w49a, all of my tools get mended for one pixel on the durability bar, but from there on does nothing. My other tools don't get the xp, and even if i take them out of my inventory, my stuff still barely repairs. I also know that I am getting so many levels worth of xp from my mob grinders, so it doesn't need any more xp to effect the durability bar. I am very confused.