I use 800 dpi with 2.1 in-game. No issues and have racked 500 kills in the last 4 days.
The same settings I used for the PUBG invitational and CSGO tournaments with quick scouting.
I am using the Logitech G PRO Lightspeed but if you are using a cheap mouse with high dpi claims then you might have issues with some games.
What helps support people is a way to understand your issue, a blank statement saying aiming is broken because it feels that way helps no one.
Hit reg is another issue altogether as Apex is unique in the way it handles players with different pings, which is why as an Australian I have hardly any issues in playing on Singapore or NA servers.
I have 4.7k hours in CSGO, 3.6k Hours in PUBG, over 2k Hours in Warzone and have been playing Apex on and off since release. Zero issues.
Screaming for a developer who couldn't help you anyway makes you look quite silly.
In the IT world most developers code, designers design and support do exactly that, support. The support staff will find bugs that developers do not know exist and replicate them so that developers can spend sometimes weeks or months trying to figure out why the bug is there.
While i appreciate your frustration there are a few guides which you could actually try to help your issue - if an issue exists at all.
Provide a short video Hit the Windows Key + Alt + R to start screen recording and then they could better understand your issue to provide the correct steps to help you.
Make sure you have your performance monitor showing and maybe go in to your game graphics settings so they can understand the load you are putting on the machine.
Some machine specifications would also help, cpu/gpu/hd/ram/mouse model, wired/wireless, BT or 2.4ghz if wireless etc.
You need to help them before they can help you.