Happened to me, my account was banned because I was using it from a restricted country (I used a VPN), for some time it worked fine, then after that ban hammer, all other accounts that used my machine later on got banned. I recall that I read online that they track your MAC address that gets attached to the build artifacts when you upload them to the store and used to link the accounts together, it's even mentioned in their banning email "Your account is associated with another banned account...".