@xunilog: Have encountered what you are describing earlier in my distro hopping days going back several years, however attributed it to my graphics card or mobo. Haven't had such an occurrence since a complete machine rebuild and update a couple years back. Scrambled pixels is what I observed and simply didn't further looking at the distro.  The distros were not zephyr or any of which you mentioned above.

This has not occurred at anytime during the testing of my builds, difficult to find answers for something that isn't there for me to witness or remedy. My final build is well tested before uploading, then retested as a download to insure the integrity of the build. More often than not a second set of eyes is used during the final builds, this issue has never been witnessed or addressed.

Not sure if you were using a disk or USB, either way something could have been corrupt not allowing a good graphics rendering. Configs for all distributions vary, certainly pertains to different DE's and Wm's. The base for all Devuan distos should be relatively the same depending on their package list. There was a period where Xorg drivers were still being pulled from Debian, not sure if this could been the issue.

Wish I could help you more, if I run into the your described issue will let you know what I did to fix it.

Cheers

zephyr