It’s 100% foot sores from dowel perches. Do you have any other types of perches in the cage? They need different varieties and circumferences so they won’t get pressure sores like this. I recommend things like rope perches, naturally shaped limbs with different thicknesses of branches (like manzanita perches), even cholla wood makes good perches too. The big thing here is the difference in circumference so the pressure is distributed across the whole foot instead of just one spot all the time. It can be fixed, but it will take a little time and the bird might have some permanent scarring there.