Hi Nicolas, apologies for breaking your system :( Is is possible for you to try and bisect the history to find the culprit commit?

It is a bit circumvoluted, but it worked properly on my side on
guix@478b9ccea8. Do you see a reason why your patches could break my
user login?

I'm not sure, I was wondering: do you use/extend the subids-service-type in your configuration or did you already have manually setup /etc/subuid or /etc/subgid? Otherwise I'm not sure how it can impact your system, if you could share even some parts of your operating-system configuration it would make finding the problem a little easier.

Since you mentioned PAM, these two changes that I authored were recently merged. Could you try and see whether your system work at commit a1ecd7f56c4ffadc49d5501a0df7f4c4556120c2 which is the parent of the first pam change?

Thank you very much :)