Father Andrew discusses two possible forms of the Zonaras Proviso.
One form is the proposition that all seven (eight in the diaspora) days of the Rabbinic Jewish Feast of Unleavened Bread must be over before Julian Easter can occur. He refutes this by pointing out that Julian Easter often falls during the Rabbinic days of Unleavened Bread.
The Resurrection itself would violate this form; see Re: TOWARDS A COMMON DATE OF EASTER: REMAINING FAITHFUL TO NICAEA
, Unleavens 3 -- a reductio ad absurdum
The other form of the Zonaras Proviso that Father Andrew refutes is the proposition that only the first day of Rabbinic Unleavened Bread (the 15th of Nisan) must be over before Julian Easter can occur. He refutes this by pointing out that in some years, Julian Easter is a week after Gregorian Easter even when Gregorian Easter is after the 15th of Nisan in the Rabbinic calendar. So the difference between Julian and Gregorian Easter (he argues) must be due to some cause other than the Zonaras Proviso.
Thus the one week difference this year, 2022. An extreme case is 2013 considering "...the earliest Passover currently falls on 26 March (as in AM 5773 / 2013 CE)" Implications for Jewish ritual
]; and from Aleppo: