New Nintendo Switch system icons based on Pokémon Scarlet and Violet have been added for Nintendo Switch Online subscribers. Different icons will be available for 6 weeks from August 9th, 2023 to September 18th, 2023.

Week 1: August 9th to 16th, 2023: Mewtwo and Mew
Week 2: August 16th to 23rd, 2023: Nemona and Arven
Week 3: August 23rd to 30th, 2023: Rika and Poppy
Week 4: August 30th to September 6th, 2023: Ogerpon and Terapagos Terastal Form
Week 5: September 6th to 13th, 2023: Koraidon and Miraidon
Week 6: September 13th to 18th, 2023: Pikachu and Eevee

Source: https://topics.nintendo.co.jp/article/eec94181-e36b-47b2-912a-41c42ad3fe9f#icon and https://twitter.com/NintendoAmerica/status/1689758528083206144