Virtual Terminal practically unusable: GeForce RTX 20160 SUPER on Slackware 14.2

My computer is configured to boot into runlevel 3 (CLI). All of the boot text scrolls by normally before the login prompt, but once the login prompt appears the display starts acting weird: not all typed characters appear and whenever a new line appears (e.g. after pressing ) the text display gets garbled in unpredictable ways.

However, after typing “startx” to start KDE the graphical environment looks normal and is usable. (The screen may display " tar_x", for example.)

Then, if I try switching back to a virtual terminal (Ctrl-Alt-F2), I just get a black screen. When switching back to the graphical terminal (Ctrl-Alt-F7), the colors are all messed up. Text in Konsole and GVim is not readable at all. Some graphical programs (e.g. NVIDIA X Server Settings) are still readable.

So, if I just boot up and start a graphical session the computer is usable. Virtual terminals are practically not usable before starting a graphical session due to the text being garbled. After starting a graphical session, I cannot switch to a virtual terminal as the computer becomes practically unusable.

I attached 3 different log reports:

nvidia-bug-report.Slackware-PreVTSwitch.log.gz: Booted computer up, started KDE, and computer is usable.
nvidia-bug-report.Slackware-PostVTSwitch.log.gz: After starting KDE, switched to VT2 and then back to KDE (VT7) and the desktop has the weird colors.
nvidia-bug-report.PopOS.log.gz: Computer came pre-installed with Pop!_OS. Here, I can switch back and forth between virtual terminal and GUI with no corruption. Since everything works fine thought I’d also include this log.

Edit: I also included a picture of what the corrupted graphical screen looks like.
nvidia-bug-report.Slackware-PreVTSwitch.log.gz (536 KB)
nvidia-bug-report.Slackware-PostVTSwitch.log.gz (563 KB)
nvidia-bug-report.PopOS.log.gz (338 KB)

Adding “options nvidia-drm modeset=1” to /lib/modprobe.d/nvidia-graphics-drivers.conf make the problem worse: roughly the bottom-half of the screen has fixed text (I guess leftover text from the initrd boot process) that always overlays what should be visible, so I can’t see what I’m typing in runlevel 3.

Edit: In the 5.4.x kernel series I’m experiencing the same behavior, so upgrading the kernel from 4.19.x makes no difference.