Is the widespread adoption of a custom among Muslims, a custom with a disbelieving origin, remove from it the characteristic of imitation of disbelievers, and is its original practitioner considered to be imitating them?

Islam has forbidden imitating disbelievers in matters specific to them. The prohibited imitation is defined as the imitator doing something that is specific to the one being imitated. So, if something has become widespread among Muslims and is no longer exclusive to disbelievers, wearing it is not considered prohibited imitation, unless it is prohibited for another reason. Al-Hafiz Ibn Hajar and Al-Allamah Al-Uthaymeen have pointed to this principle, stating that if something was a symbol of disbelievers but is no longer so, the disapproval of imitating it vanishes. However, if a Muslim started doing it before it became widespread among them, he is considered an imitator.