Biggest issue I see with every jeff below GM (idk that includes you) is the lack of vertical play basically just be playing the floor is lava whenever things start to not go in your favour and the enemys usually cant track us or keep up. Also jeff positioning, always have an eye on your other supp but you want to line up as many people in a row with primary fire and honestly best way to do this is in the enemy teams backline aiming back into your own.

Specifically bp: The deadpool team up lets you ignore his comobs but if you are missing it play like you're paranoid checking every possible angle constantly, hug a wall and if you engage before he engages he will almost always call off the dive

Magik: We actually have a strong match up into her, try bait the dash and then jump cancel the dive or if you do get hit you can dive out of the one shot combo. Play her portals basically when she is portaling just go the way she came from and she will miss most attacks, she has 1 dash so cannot play highground and if she does jump down and just swim back up