Power sequence bugs cause damaging flickers on built-in displays. Update now.
For desktop Linux users, updating to a new Linux kernel typically carries relatively small, contained risks: wonky drivers, GRUB pain, maybe a full wipe and reinstall. For one subset of laptop owners on rolling release distributions, however, kernel version 5.19.12 could cause actual LCD screen damage.
"After looking at some logs we do end up with potentially bogus panel power sequencing delays, which may harm the LCD panel," wrote Intel engineer Ville Syrjälä in a discussion on the issue. "I recommend immediate revert of this stuff, and new stable release ASAP. Plus a recommendation that no one using laptops with Intel GPUs run 5.19.12."
One day later, kernel 5.19.13 was released. But there's a distribution chain between kernel work and distribution desktops, and certain laptop owners were caught up in it.
"Two days ago, I updated to kernel 5.(19).12, and my screen now flickers rapidly," wrote user CrepeDragonball in the r/framework subreddit for owners of the Framework laptop, which contains an Intel Iris Xe integrated GPU. "I can see the flickering even on UEFI (BIOS), so I think it is hardware related, not OS/driver related. ... The flickering is at such high rate[s] that I can't capture it with my phone camera." Similar reports came up in ArchLinux and Fedora forums and subreddits, along with Framework's official forum.
Some users reported flickering that didn't go away after reboots or after switching to base-level tools like BIOS or GRUB. A few managed to switch their kernel versions by connecting to an external monitor and saw the flickering gradually fade with time. But panel power sequencing (i.e. screen timing) gone awry can permanently damage screens, especially the LCDs integrated into laptops. As of this posting, the original poster to the Framework subreddit has not posted about his screen being restored.
Linux kernels and distributions doing physical damage to desktop hardware is rare but not unheard of. Mandrake 9.2 was found in October 2003 to be capable of killing specific LG CD-ROM drives. The cause could have been kernel code, LG's firmware, or both, according to an update on a Linux.com post about the issue. LWN.net noted that LG Electronics did not support or test hardware with Linux.
More typical is hardware being written to, or operated, out of specifications; many veteran hardware programmers attest to this time-honored tradition in an unusually intriguing Quora thread.
It's a good idea to update your Linux kernel beyond 5.19.12 if possible or otherwise downgrade, even if you're not immediately seeing graphical issues.