Upon further investigation, I think it is very unlikely this misbehavior is due to the gnome-keyring debian package. The relevant code in upstream[1] is very old. It appears to check for the existence of both dirs and prioritizes the new one if both dirs exist. The creation timestamp for the new dir is a few days older than the upgrade. So likely gnome-keyring-daemon was started prior to that new directory being created and the dist-upgrade simply prompted a reboot, which led to the daemon recognizing the new directory on the next start.
[1] https://gitlab.gnome.org/GNOME/gnome-keyring/-/blob/main/daemon/dbus/gkd-secret-service.c#L170-186
