I dont think we can judge Leclerc too harshy, any driver would struggle with a car that randomly oversteers or understeers into the same corner on different laps. It makes it incredibly difficult to have any confidence and really push.
How Ferrari still havent managed to figure out the underlying issue is strange. It maybe a fundamental flaw in the car that can only be fixed with next seasons car.
Not as bad as the ferrari issue, the mercs have an issue with corners when hitting the apex, theres a deadness to the car which means their drivers dont know if the car will stick to the apex line or understeer. This then causes issues with confidence going into the corners.
Basically, we arent really seeing leclerc/sainz/russell/hamilton go 10/10ths and really push, as they dont have the confidence in the cars. This is making the gap bigger to the RBs.