Meta-Brilliance: The entire shows resurgence back in 2017 came at possible the most perfect time due to the rise and resurgence of more multi-cultural British celebrities, Grime, Afrobeat & Afroswing music with stars such as Stormzy and was released during the peak period of Brexit, leading to the show is going to gaining more popularity due to it tackling issues more apparent UK. Being funded by Netflix and Drake definitely helps.
Why is Sully in later seasons ,particularly Season 3, less Ax-Crazy than he was back in season 1 where he had no remorse for accidentally killing an innocent man or about the death of Leon. Well in season 2 hes working as a gun-for-hire so hes killed more people and is less Hot-Blooded and eager to prove himself as a bad man. In season 2 hes colder, which is possibly due to his partnership with Mike who is even more of a Leeroy Jenkins than he ever was due to his mental instability. By Season 3 Sullys just finished serving a sentence in prison so hes had time to calm down and loosen up some of his excessively violent tendencies and after Jasons death hes clearly in a state of trauma and possibly PTSD which along with his tiredness from how long hes been on the Road, is making him wearier and wearier as well as less inclined to get to the top than Dushane because hes already lost and suffered more.