I'm building a new rack server (Poweredge R620) and am using the option "consoleblank=600" in the GRUB_CMDLINE_LINUX setting. During the setup I used the wrong memory stick and installed Bullseye, and screen blanking was working correctly there. Since I had already finished nearly all the configuration this week, I thought it would be easier to just do a regular dist upgrade than reloading the whole system.

After upgrading to Bookworm and rebooting, I notice that now when the screen blanking is supposed to kick in (which normally just turns off the display), I am instead getting what looks like rolling static on the screen. I have several other R620 racks running Buster so I know the screen blanking should work with this hardware, but this appears to be an issue specific to Bookworm.

Note that even when I try something like setterm -blank 1 or setterm -powerdown 1 I get the same resulting static after 1 minute. To be clear, this is specifically for the command line, I do not run desktops on my servers.

A google search for the problem has been unsuccessful so I'm hoping someone can point me to a solution or help with the proper search terms.