[mantic] rpi3 has no video output on HDMI

On the mantic beta (20230919.1) I don't see any video output on hdmi with rpi3. I've tested the same image and configuration with rpiz2 and rpi4 so far, and I do get hdmi output on both of those, so I don't think it's likely to be an issue with my monitor or cable. Logs attached.

ProblemType: Bug
DistroRelease: Ubuntu 23.10
Package: linux-raspi (not installed)
ProcVersionSignature: Ubuntu 6.5.0-1002.2-raspi 6.5.0
Uname: Linux 6.5.0-1002-raspi aarch64
ApportVersion: 2.27.0-0ubuntu2
Architecture: arm64
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/controlC1', '/dev/snd/pcmC1D0p', '/dev/snd/controlC0', '/dev/snd/pcmC0D1p', '/dev/snd/pcmC0D0p', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: N/A
CasperMD5CheckResult: unknown
CloudArchitecture: aarch64
CloudID: nocloud
CloudName: unknown
CloudPlatform: nocloud
CloudSubPlatform: config-disk (/dev/mmcblk0p1)
Date: Thu Sep 21 17:04:47 2023
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
Lspci:

Lspci-vt:

ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=vt220
ProcFB: 0 BCM2708 FB
ProcKernelCmdLine: coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_headphones=0 snd_bcm2835.enable_headphones=1 snd_bcm2835.enable_hdmi=1 bcm2708_fb.fbwidth=1920 bcm2708_fb.fbheight=1080 bcm2708_fb.fbswap=1 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 console=ttyS0,115200 dwc_otg.lpm_enable=0 console=tty1 root=LABEL=writable rootfstype=ext4 rootwait fixrtc quiet splash
RelatedPackageVersions:
 linux-restricted-modules-6.5.0-1002-raspi N/A
 linux-backports-modules-6.5.0-1002-raspi N/A
 linux-firmware 20230919.git3672ccab-0ubuntu1
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux-raspi
StagingDrivers: snd_bcm2835 bcm2835_mmal_vchiq bcm2835_v4l2 bcm2835_isp bcm2835_codec vc_sm_cma
UpgradeStatus: No upgrade log present (probably fresh install)
acpidump: