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To me that just looks like a broken scale, or has been chewed off by a cricket. I wouldn't worry too much as Beardies are quite resilient, their scales too. Just make sure there is no live food lurking in the tank and keep an eye on the elbow to ensure it isn't getting worse.
Looks like just a damaged scale, keep an eye on it and see if it changes like getting black in color.. You can use some betadine solution weakend with water to look like weak tea and do a little soak..