Problem:

Despite reinstalling everything I can think of I am having an issue with certain highlights tearing. This issue has been present for me in both GNOME and KDE.

It seems to appear consistently while using Firefox and KDE Plasma 5 desktop, however I have seen it happen in other applications (ex: Ubuntu Settings and Dolphin). It seems only to happen in certain programs: Slack, VS Code, Atom, Gimp, and Google Chrome, have never given me problems.

All the tears seem to be from highlighting something or hovering over a button. Maybe the commonality is something to do with performing a fill?

I'm not the most experienced with Linux so I am thankful for any help.

I believe this person is having the same issue

Examples:

Graphics Info

andrew@qis:~$ glxinfo -B
name of display: :0
display: :0  screen: 0
direct rendering: Yes
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: Intel Open Source Technology Center (0x8086)
    Device: Mesa DRI Intel(R) HD Graphics 2500 (IVB GT1) (0x152)
    Version: 20.2.6
    Accelerated: yes
    Video memory: 1536MB
    Unified memory: yes
    Preferred profile: core (0x1)
    Max core profile version: 4.2
    Max compat profile version: 3.0
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.0
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) HD Graphics 2500 (IVB GT1)
OpenGL core profile version string: 4.2 (Core Profile) Mesa 20.2.6
OpenGL core profile shading language version string: 4.20
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile

OpenGL version string: 3.0 Mesa 20.2.6
OpenGL shading language version string: 1.30
OpenGL context flags: (none)

OpenGL ES profile version string: OpenGL ES 3.0 Mesa 20.2.6
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00
andrew@qis:~$ lspci | grep VGA 
00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200
v2/3rd Gen Core processor Graphics Controller (rev 09)

System Info:

Operating System: Ubuntu 20.04
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8
Kernel Version: 5.8.0-55-generic
OS Type: 64-bit
Processors: 4 × Intel® Core™ i5-3470 CPU @ 3.20GHz
Memory: 15.5 GiB of RAM

mesa-utils/focal now 8.4.0-1build1 amd64
qt5-style-kvantum/focal,now 0.20.0+repack-1~focal1 amd64

Compositor Settings (these are the defaults):

• Scale method: Smooth
• Rendering backend: OpenGL 3.1
• Tearing prevention: Automatic When I tried fiddling with these, things started getting weird so I reset them, however I am willing to fiddle more.

If you need any more info just ask. But please someone help me!

Exact same issue experienced - affected firefox also (unless webrender was set to force disabled). However I was using linux-image-5.8.0-55-generic:amd64. Reverting to kernel initrd.img-5.8.0-48-generic temporarily resolves the issue - but obviously cant stay on a kernel with patched security vulnerabilities.

Switching to (latest) kernel 5.4 permanently resolves the issue - however would like to know if some work is going on to rectify the issues with 5.8?

Do not change anything before reading the whole answer. Last line is particularly important.

Try setting environment variable __GL_YEILD=USLEEP. This fix, which I found here, was posted for a different graphics card, but fixes the same issue in KDE Plasma 5/ Kubuntu. I also noticed that the OP in the question you linked was using Plasma 5. Seems like a pattern, no? Maybe an issue with their implementation of OpenGL? I'm pretty sure this fix will work across all Plasma 5 setups.

Anyway, the video recommends downloading his homemade shell script and placing inside the Plasma 5 config folder in ~/.config/kde-workspace/env/, however:

• this is for another system, so the folder structure may be different. If so, you can refer to the Plasma 5 help docs, or else the website for the location of your environment config folder, if you see some advantage that I overlooked to using a script.

• Also, I don't recommend downloading anything, especially an executable, from a random website/ video description. I am sure you know why. The script only contains one line: export __GL_YEILD=USLEEP. As it is being exported, I am pretty sure that runniing it from the command line will have the same effect.

Anyway, if this does not work, be sure to set it back to it's original value. Run 'set' command from command line before exporting, so you can get the original value, if it is already set.

Like @paul-dev said, downgrading to the 5.4 kernel series solves the problem with the advantage of, instead of having to stay on a kernel version without security patches (because if you update it, you get the bug back until it is solved), having 5.4 kernel you get latest security updates avoiding this problem at the same time.

@paul-dev report that issue on Launchpad: https://bugs.launchpad.net/ubuntu/+source/linux-signed-hwe-5.8/+bug/1934652. It would be convenient that those affected by this bug to notify it and also indicate what graphics card and processor they have to help developers to solve it.

And meanwhile, the problem may be avoided installing 5.4 kernel series. You can take a look at this information for doing that: https://wiki.ubuntu.com/Kernel/LTSEnablementStack

In this case you must track to GA kernel. Be sure to boot on GA kernel prior to remove any HWE kernel. Before remove any 5.11 or 5.8 kernel you must check with uname -r that you are working from the 5.4 (GA kernel). Install 5.4 first, boot on it and after that remove 5.8 and/or 5.11 series: https://askubuntu.com/a/1310623/433685