So far, nothing. Just in case it helps someone else who wants to try, I found that the X11 config files are in /usr/share/X11/xorg.conf.d/ in Debian-based distributions. Apparently this per new-fangled Xorg standards but it was a bit of a curveball. They can be moved into /etc but needn’t be.
I have tried creating 20-intel.conf in the above location per the other thread @RandomUser quoted:
Identifier "Intel Graphics"
This created artifacting in the screen (splotches of color in static areas like the desktop background, ghosting from window dragging or maximizing in static areas of the screen, artifacts left over in letterboxing bars on video playback, etc.). Adding the:
Option "TearFree" "True"
to that configuration does indeed fix tearing, but the other artifacting is so bad that it is not a viable solution. It makes using the computer extremely annoying. I also tried changing acceleration method to no avail.
I did both of these things both before and after running the 20.04 automated setup scripts. Those appear to be good to run anyway, so it isn’t effort wasted.
At this point, I think it’s back to Wayland, where the behavior was better. Wayland is very slightly less sharp than X11 (which is why I wanted to revert to X11), but it is pretty subtle. I suspect the effect would be invisible if not for the display on this machine. Framework’s screen is incredibly good.
With Ubuntu+X11’s choices apparently limited to “put up with tearing” or “put up with constant artifacting” when using fractional scaling, I think it is not worth the effort to chase diminishing returns. If anyone else’s experience is like mine when using scaling (especially fractional scaling) on Ubuntu, Wayland gives me a much better experience and the downside, if detectable, appears to be extremely minor. If your applications don’t fight with Wayland (some do, and require X11 to work properly), it’s probably the best move.
For anyone unfamiliar with the process, here is how you get into Wayland on Ubuntu:
- Select your username on the login screen
- Click the gear wheel in the lower-right corner
- Select “Ubuntu on Wayland” from the menu
- Log in
Thanks to @RandomUser, @Jeremiah_Jones and @2disbetter for your input.