I would say a form of viburnum. Cut off a branch with a few leaves and take it to a garden center (not big box...)

Did it ever flower?

Thank you for your comment! I don’t remember it flowering. Good idea to cut off a branch and to take it to a nursery. Appreciated!

I believe there is an APP called Seek that might identify it for you on your phone. Looks like a privet to me, but I'm not sure.

Looks very much like the viburnum we had in FL - they grew like mad. White round-ish flowers every once and awhile.

Does your neighbour not know what they planted? That would be my first stop.

He does not remember, unfortunately.

Does look like ligustrum aka privet. Grows all over SoCal.

Usually kept trimmed for privacy or background purposes so the small flowers are not too noticeable.

Looks like Privet. My mother in law had a whole hedge of it. When it bloomed I ran for cover. Highly allergic to it.