Sibley signed for Palace in 2022 and featured six times in the promotion-winning campaign of 2023/24.
She then joined Newcastle United on loan for the 2024/25 season, making 11 league appearances and scoring three goals for the Magpies.
Sibley leaves the club having made 20 league appearances, scoring one goal.
Everyone at Crystal Palace would like to thank Isabella for her contributions and wish her all the very best for the future.