Found pill says G254 on it its white what is this?

The pill imprinted with "G254" is identified as Diphenhydramine Hydrochloride 25 mg, which is an over-the-counter antihistamine commonly used to relieve symptoms of Allergies, hay fever, and the common cold. It can also be used as a sleep aid due to its sedative properties. Always consult a healthcare professional before taking any medication to ensure it is appropriate for your situation.