The Pi Zero 2W, 2B, and 3B all fail to light their power LED once the kernel starts booting under noble (I hope this is only on noble; I only just noticed this during ISO testing and it's quite possible I missed it on earlier revisions...).
Specifically, on the 2W (which only has a combined activity and power LED), /sys/class/leds/ACT/trigger is [actpwr] on RaspiOS, which makes it illuminate by default and blink off during mmc0 activity. This trigger setting appears to be unavailable under the Ubuntu kernel.
On the 2B and 3B, the trigger is set to [none] which results in the LED initially illuminating while the bootloader is running and then disappearing. The default under RaspiOS is [input] which makes it illuminate normally, but switch off on undervolt. This trigger settging also appears unavailable under the Ubuntu kernel.
This bug has been reported on the Ubuntu ISO testing tracker.
A list of all reports related to this bug can be found here:
http://