Why are GOOG (not voting shares) still trading at a premium to GOOGL (voting shares)?

I bought GOOGL around 10 years ago when it was trading at a premium to GOOG because the shares had voting rights. Google then started doing buybacks on GOOG and not GOOGL which caused GOOG to overtake GOOGL in share price which makes sense. Due to what I think was shareholder feedback Google started doing buybacks on GOOGL alongside GOOG.

So my question is, since Google is now doing buybacks on both GOOGL and GOOG, why are the non-voting shares still trading at a premium?