Last Sunday was Pentecost Sunday. All of the vestments and liturgical cloths were red. When does the Easter season end?
The Easter season ends on Pentecost Sunday. The liturgical color of that day is red in honor of the Holy Spirit. Occasionally the liturgical colors change within a season (e.g., rose on Gaudete Sunday in Advent and Laudare Sunday in Lent), but that does not necessarily mean the season itself has changed.