After the destruction of the temple in 70 AD did the people change from figuring the Shabbat from the new moon to picking a day like Saturday because of persecution from the Roman Empire?

ב"ה Shalom The Shabbat is not based on lunar calculation but simply by counting the days of the week from time immemorial. On the other hand, in regard to the determining of the holidays which does follow the lunar cycle, although the Roman empire went through a drastic change in the first century and started following the Julian calendar, the Jewish people despite persecution and being under foreign rule, ardently adhered to the Jewish calendar. All the best