https://autos.yahoo.com/max-verstappen-penalized-post-race-230100577.html
"...Because Verstappen decelerated significantly and unexpectedly, he escalated the situation from an odd miscommunication to an actual collision. As a result, he was penalized what the stewards would typically give a driver for causing such a collision. It does not change the result of the race at all, of course, but it represents an official declaration that Verstappen did the wrong thing and an official precedent about the action going forward."