It appears the main cause of this is presently bug 1959888 when you log in with a secondary monitor on a secondary (Nvidia) GPU. So the log messages stop once you have that fix. Although I would still like to understand it better because that's the second bug I've seen trigger the same messages.
** Changed in: mutter (Ubuntu) Importance: Undecided => Medium ** Changed in: mutter (Ubuntu) Status: New => In Progress ** No longer affects: nvidia-graphics-drivers-510 (Ubuntu) -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/1967707 Title: Nvidia Wayland sessions sometimes flood the log with [clutter_frame_clock_notify_presented: code should not be reached] To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/1967707/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs