I tested both Xubuntu 20.04 and Ubuntu MATE 20.04 And I had the very same issue, however I have a single display, 3440x1440, using AMD RADEON VII GPU. Kubuntu 20.04 and Ubuntu Budgie 20.04 do not have this issue.
Originally I opened a separate bug but it was marked as duplicate. I wanted to confirm the same issue is still there. After testing 20.04.1, making both xubuntu and ubuntu MATE unusable unless compositor is disabled as suggested in this bug report: https://bugs.launchpad.net/ubuntu/+source/marco/+bug/1876480 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1873895 Title: Regression: block staircase display with side-by-side monitors of different pixel widths To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1873895/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs