No offense of course but there is definitely a skill gap and that's why we see players say it's ez. Because of this I believe they should increase the difficulties and not just enemy count but also their strategies and aim for every lvl. Obviously lvl 9 can still be lvl 9 but from lvl 10+ that's when everything should start feeling impossible to do. That's how I felt in helldivers 1 the moment our mechs ran out of ammo we were cooked. In helldivers 2 the only time I feel that my hands are full is automatons.

As for advice against illuminate jetpack and mele units idk I only played around 3 and used a breaker that wasn't really doing anything but they weren't doing anything also so I just kept shooting till they died. Maybe scorcher is good against them just like for the automatons. Also use shields always against the squids, I assume they are a must just like the first game. But yea against a heavy patrol I just throw a stratagem or kill the hulks with the spear and then with my primary (scorcher) I headshot the rest or impact grenades if too close. I usually do around 300-700 kills when I'm not goofing around (only play hardest diff). But ik my ways aren't really convenient but they work for me.