#4 Restarts are always eventful

Spa-Francorchamps' run from La Source to the Les Combes chicane used to be the longest full-throttle stretch in Formula 1 racing before Baku's addition to the calendar in 2016.
The mammoth stretch from Turn 16 to Turn 1 is the longest in terms of acceleration and it comprises the entire third sector and a small section of the first. This means that the slipstream is extremely effective and differences in engine performance are multiplied, increasing overtakes after a Safety Car restart.
Just ask Daniel Ricciardo, he overtook Felipe Massa, Nico Hulkenberg and Lance Stroll in one manoeuvre in 2017, which effectively set him on his way to a victory that day. Whatsmore, the Red Bull was powered by a Renault engine, one that was underpowered compared to the Williams-Mercedes vehicles. It is still difficult to overtake, but far from impossible like some circuits (Monaco or Singapore).