This is a good page about Easter calcs and common Myths found on the internet.
Easter is based upon Paschal Full Moon (PFM) dates and NOT
Astronomical Full Moons dates, and each (PFM) is the particular Ecclesiastical Full Moon (EFM) date after March 20,
Provided it does not coincide with Passover.
Yes, it is complicated!
At the bottom of this linked webpage is a list of differing calculation methods.