I have these lines in /etc/pam.d/kde and /etc/pam.d/sudo:

# /etc/pam.d/kde
auth      sufficient     pam_u2f.so      openasuser

# /etc/pam.d/sudo
auth     sufficient     pam_u2f.so      authfile=/etc/Yubico/u2f_keys cue

Sometime in the last week pam_u2f stopped working.

On any sudo commands, I need to confirm on my U2F device, but then I get asked
for the password.
Same on KDE session unlocking, I need to enter the password. In addition, the
login prompt does no longer get replaced by an "unlock" button as soon as I
confirm on my U2F device.

As pam_u2f had the last update 5 months ago, I suspect changes in other
packages (pam?) as the reason for the breakage.

Did not have much time to go looking for logs, also not sure where pam logs to?

Kind Regards,
Johannes