Comment 3 for bug 1976147

> Do you see the rainbow splash?
Yes

> Is the monitor in stand-by and wakes up later during the boot process?
Yes. But in a "normal" boot (e.g. Ubuntu 21.10) it also made a quick jump from "on to stand-by to on" at middle of the boot. The difference is that in Ubuntu 21.10 boot messages are shown from the beginning so are shown before and after that jump. In Ubuntu 22.04 boot messages are not shown until that jump occurs.
I've made two videos showing the boot process in Ubuntu 21.0 and Ubuntu 22.04 (both fresh installs only removing quiet and splash options from cmdline.txt). I'll attach these videos in a later posts.

> Can you try a different monitor?
Yes, tried 3 devices (two monitors and a TV) and all of then shows the same problem.

> Can you try 5.15.0-1012.14 from -proposed?
Yes. Tested and still the same problem.

I've also tried Ubuntu's current critical bootloader (pieeprom-2022-01-25.bin) and the newest one available from Raspberry Pi Foundation (pieeprom-2022-04-26.bin) and got the same problem in both.

Also tested current Raspberry Pi OS (64 bits) that come with a 5.15 kernel as Ubuntu 22.10 and it works as expected: boot messages are shown from the beginning of the boot process.