Still paniking, cause the backdoor was apparently targetting Debian servers, it was discovered just by chance and the "mantainer" made commits for 2 years in the same repo
and it was only discovered accidentally, when someone was profiling some stuff, noticed SSH using a bit too much CPU power when receiving connections even for invalid usernames/passwords, and spent the time to investigate it more deeply. A lot of developers aren't that attentive, and it could have easily snuck through.
I've never read your blogs but I think it would be good for more people to do write ups on the XZ backdoor. There is a lot that can be learned and improved