[Green314]

You aimed too high, trigger an investigation that linked together the accounts (when they didn't really care before) as well as new one
No, amazon can't see your MAC address (unless you're using the app on the phone, then maybe it's doable, but a website cannot access those information)
If you're using a VPN, maybe they blacklisted that range of IPS
If you're just resetting your router for a new IP, they could've blacklisted the area that geolocates the IP
Or, most likely, you always had a flag on all accounts and just went under the radar with low refunds until now, but you're red flagged now, and it's gonna be a pain to get a new account

This ^.