Everytime Leclerc sees a Mclaren he goes into a "do or die" mode, while giving up right away when fighting against Lewis.
Leclerc was imho the biggest factor. The guy has a problem with Mclaren.
Worth bearing in mind, Oscar would have been straight into DRS of Lec if he'd nailed his stop. 2 seconds lost would have got him to Ham by lap 42. Except he'd not have fought Lec for so long, so probably sooner.