It’s an Apple band. Bought it from the Apple store.
It's still be under warranty so Apple will replace it. Seems the solo sport loop has had problem's splitting/cracking so it may happen to the replacement tooI haven’t. I guess it doesn’t hurt to try, I’ll try online first. But ya, I wasn’t sure if I did something on accident to cause this or if this was normal. Wish these bands weren’t so expensive!