The Digital Clock widget isn't formatable anymore, which leaves the configurability quite limited. * Missing dialogue to set custom time and date formats. (e.g. ddd dd. MMM hh:mm) * Not possible to set horizontal viewing of time + date (only stacked, which isn't good for horizontal panels). (I distinctly remember these options having been available in a/the default clock widget at some earlier point in history)
bug 340982 is related to time and date formats. Please create a report for each issue. https://community.kde.org/Get_Involved/Bug_Reporting#One_issue_per_bug_report
I've added one bug report for each of the bullets: Missing formatting: https://bugs.kde.org/show_bug.cgi?id=393956 Only stacked time+date: https://bugs.kde.org/show_bug.cgi?id=393957