There are other threads that mention this 404 error after submitting the form, it's more than 4 months the form is broken, at the beginning it was working one time after 20-30 attempts, now it doesn't work at all, people reported this issue but we've been completely ignored because "it works on your side", it's clear there's something wrong and it should be investigated since the form is the only decent way we have to report cheaters. Other alternatives to report players have relevant limitations.
For example:
Reporting issues goes right to 404 not found. | EA Forums - 13213333
Hacker Report 404 Error | EA Forums - 13275937Hacker Report 404 Error | EA Forums - 13275937
And many others
EA_Darko I get that it might work on your side but I've been trying for months, different browser, different device, different connection, I've been able to report only one or two cheaters out of twenty (more or less), and for each cheater I tried to submit the form 20-30 times or more using as I said, different devices, different browsers, different connections (also mobile), trying in different moments or days.