Was v were, subjunctive or not

I have tried researching this topic on grammarly and on this website ("Was" or "were" in subjunctive clauses), but still am unsure.

Which is correct?

His gaze turned up, as if there were an imaginary light bulb there.

Or

His gaze turned up, as if there was an imaginary light bulb there.

I say “were” because I think this is subjunctive, but my friend says it’s “was.”

Thanks