It mentions this GDID is sent in telemetry. So this guy kept using a hosted proxy, meaning his egress IP was always changing accessing different services, but everytime his Windows 11 machine was sending back telemetry (which included his GDID) they were logging the IP address he was appearing from (the proxy) - so they were able to track and identify him.
If you use your Microsoft account to login, they have to be able to identify you somehow when you try to authenticate. It is basic usage. Not Telemetry. That is what caught him.
It mentions this GDID is sent in telemetry. So this guy kept using a hosted proxy, meaning his egress IP was always changing accessing different services, but everytime his Windows 11 machine was sending back telemetry (which included his GDID) they were logging the IP address he was appearing from (the proxy) - so they were able to track and identify him.
If you use your Microsoft account to login, they have to be able to identify you somehow when you try to authenticate. It is basic usage. Not Telemetry. That is what caught him.