Every maker just uses an adhesive on that part. That probably happened because you kicked something, and it just caught the leather. It looks like you did, On the left side of that, facing us, I see that there is a bit of black that is worn off on both the upper and the midsole. That happens if you catch something. fwiw, I constantly fidget my feet, and kick at things, and this happens to 95% of my shoes. So I just use use some Freesole, which is what pros use to do repairs, and do a quick repair home repair.. You just apply a bit, then apply pressure for 12 hours, and you are as good as new.