How do I aim in higher ranks?

Hello, i first started playing comp this season, as before I was a quick play warrior. Got from bronze-gm already, but an issue I found is that now that i’m a higher rank and people know how to strafe and move better my aim has gotten SO much worse. When I was in lower ranks (i main black widow/phoenix/hela and hawkeye when not banned) i was hitting every shot left and right, getting mvp every round, and the same goes for quick play. Now that I’m gm im struggling to hit a lot of shots. How can I improve aim against actually good players?

My sensitivity is 3.02 with a 800 dpi, i’m thinking about lowering it a lot as well, does this see too high? Seemed good and worked good when I was in lower ranks but now i’m struggling with it.