In this case the red lights are pre-illuminated part of the way around the final pace lap and are changed to green once the starter is happy with the composition of the field.
Drivers must stay behind the pace car and maintain their position within the field, unless entering the pits or given leave to go around.
Furthermore, as the green flag nears and the pace car exits the track, drivers must maintain speed and position heading to the proper line.
The lead driver cannot slow excessively to force trailing cars to bunch up, which would give the leader a jump on the restart.
Some Formula One races — 2022 at Monaco, 1997, 2000 and 2021 at Spa, Belgium, 2003 at Interlagos, Brazil, 2007 at Fuji, Japan, 2008 at Monza, Italy, 2009 at Shanghai, China, 2010 at Yeongam, South Korea, 2011 at Montreal, Canada, 2014 at Suzuka, Japan, and 2016 at Monaco and then Silverstone, Great Britain — started with a rolling start because of weather concerns.