why is verstappen starting from pit lane

Verstappen is starting from the pit lane in Sao Paulo because Red Bull made significant setup and engine changes to the RB21 after a disappointing qualifying session, breaching parc ferme rules. The breach triggers a requirement to start from the pit lane so the team can complete the modifications without changing the race setup on the grid. This is done to improve performance for the race, given Verstappen qualified 16th and faced a lack of grip and pace in Q1.