Yes that is bumblefoot, usually from a small cut and a staph infection. There are a number of ways to treat bumblefoot. I don’t treat it unless they are limping, or have an abscess as yours does. The soaking helps daily. Some try to soften and loosen the scab, then try to squeeze out the waxy core inside. There may be some pus in the puffy areas between the toes. You may also use betadine and sugar in a bandage wrapped on the scab for a couple of days, or something like PRID to draw infection out. I have done the surgery on a few of my hens. It is easier with a helper, and having all tools and dressing materials ready, while the helper holds the chicken wrapped up in a towel. Here is some reading about treatments: https://the-chicken-chick.com/bumblefoot-causes-treatment-warning/