At first this looks like a hardware fault to me. It looks like what happens when I replace a laptop screen and it doesn't get a clean electrical connection. The same can happen if it has received some bumps and intermittently loses connections on some pins.
However there's a chance this is a kernel bug and your observation that 20.04.2 does not have a problem supports that theory... Please: 1. Edit /etc/default/grub and change: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.enable_psr=0" 2. Run: sudo update-grub 3. Reboot. Does that fix the problem? ** Package changed: xorg (Ubuntu) => linux-hwe-5.11 (Ubuntu) ** Changed in: linux-hwe-5.11 (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1950355 Title: Intense screen flickering, vertical rainbow bars, display problems on Ubuntu 20.04, Lenovo X1 Carbon To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-hwe-5.11/+bug/1950355/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp