The Istanbul stewards heard from both drivers and their team representatives in addition to reviewing multiple angles of video evidence and radio calls to the McLaren driver.
Sainz was exiting the pits as Perez passed through Turn 1. Perez subsequently caught up to the McLaren in turn 2/3 and was unnecessarily impeded by the Spaniard at that point and through several subsequent turns.
The stewards deemed that while extraordinary track conditions clearly impacted the situation, radio communications from the team clearly warned Sainz that Perez was behind him.
The Spaniard was therefore handed a 3-place grid drop and 1 penalty point, the first in the 12-month period.