It does look like the tail will fall off so keep an eye on it and apply some antibiotic cream some days, aloe gel other days. [ Must be pure aloe with nothing added ] There is trauma to the tail, possibly retained shed has cut in to the tail. It may end up falling off, but if it at any time looks infected, get to a vet ASAP. Beardies are not one of the lizards that drops it's tail for defence, the many lizards that do so have the ability to regrow their tail [ though it never looks as good as the original '] But beardies do not drop their tails naturally, only because of trauma/injury.