It's avoidance of risk that the traffic is illegitimate, not avoidance of traffic. That much traffic with no sales stands out.
Why would someone spend so much cash on ads to get probably very little sales?
It's a weird egde case that is more likely as per their experience to result in chargebacks from the few sales they got. Traffic from HN is not the normal traffic the AI is trained on.
The sad truth is when you partner with a FAANG and their likes you need to think about what they have optimised for, not what is actually good for you or them. What is the easy money they want and how would they calibrate they systems so they get more of that and less 'noisy' or even 'expensive' money?
Go for that rather than something different that raises virtual eyebrows.
It's actually much better then anything else that's probably out there for bike tires.
Amazon was just not ready for the huge traffic spike. Either relaunch with a new ID or try the support. Whatever faces less resistance.