The feast of Saint Irene of Thessalonica is April 3.
There are a number of saints named Irene, each with a different feast day. You need to be specific.

Yes, she was from Athens.

There is no St. Irene with a feast day of June 28. However, Saint Irenaeus of Lyons has his feast that day.

Saint Irene of Rome is not formally recognized as a saint by the Catholic Church, and no official canonization date exists. In some Christian traditions, she is venerated as a saint based on her association with Saint Sebastian and Saint Susanna.

Thera was Sant0rini's old name. The w0rd Thera was changed to Saint0rini because the Greeks used to call s0me things Saint Irene. Now if you read 'Saint Irene' fast and out loud (you gotta pronounce Irene as Ireni but) you would get the word Saint0rini.

H0pe this helped y'all :)