When they flash me it feels like some good 4-5 sec, but when I do i get insta-killed as if they weren't flashed, or they are flashed for like 2 sec I don't know what am I doing wrong

Hello there, I am iron 3 and was playing a competitive match on Bind as KJ and decided to use an ares as I have found it complements Killjoy's turret(basically bot pins the enemy while I finish them up). Even before the second round start...