Saw this yesterday 30th December.
Reading the strftime manpage I'd say this is normal. It says: "This year is the one that contains the greater part of the week." If you want 2019 you should use %Y.
If I remember correctly, only %V can be combined with %G.
This looks like a misconfiguration rather than a bug in either xclock or strftime?
(In reply to Niclas Zeising from comment #3) I think it's just a matter of usage. It should be used as follows: xclock -d -update 86400 -strftime '%G-%V-%u' Reading man 3 strftime makes it difficult to understand the relationship like the result of the following command: for d in $(jot 10 0) ; do date -v 2019y -v 12m -v 28d -v +${d}d '+%a %Y-%m-%d %G-%V-%u %Y-%U-%w %Y-%W-%u' ; done
This seems to be a misunderstanding of how strftime() and friends work, and not a bug in xclock? If you believe that this should be fixed in xorg, please reopen the bug.