[iris regression] gfx corruption

Hello, after upgrading firefox (and many other packages) on focal today, I've got some video artifacts in firefox.

When typing in text boxes and text fields, the new character is drawn very slowly, pixel-by-pixel, and isn't complete until the cursor has moved on. When larger portions of the screen are updated, it looks a lot like the entire window is being run through a video codec or you can see parts of the video memory from other processes. (But it looks more deliberate and predictable than either of these descriptions.)

So far Firefox is the only application I've found that is affected. urxvt, libreoffice, xfontsel, glxgears all seem to work as expected.

I did get cairo package update today, but the changelog is just:

pango1.0 (1.44.7-1ubuntu2) focal; urgency=medium
  * No-change rebuild with fixed binutils on arm64.
 -- Matthias Klose <email address hidden> Sat, 08 Feb 2020 11:15:23 +0000

And an xorg update:

xorg (1:7.7+19ubuntu14) focal; urgency=medium
  * No-change rebuild with fixed binutils on arm64.
 -- Matthias Klose <email address hidden> Sat, 08 Feb 2020 11:21:28 +0000

So I don't believe these are involved.

00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07)

Thanks

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: firefox 73.0.1+build1-0ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-14.17-generic 5.4.18
Uname: Linux 5.4.0-14-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
AddonCompatCheckDisabled: False
AlsaVersion: Advanced Linux Sound Architecture Driver Version k5.4.0-14-generic.
ApportVersion: 2.20.11-0ubuntu16
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: sarnold 3296 F.... pulseaudio
 /dev/snd/controlC0: sarnold 3296 F.... pulseaudio
BuildID: 20200217142647
Card0.Amixer.info:
 Card hw:0 'PCH'/'HDA Intel PCH at 0x2fe1028000 irq 144'
   Mixer name : 'Realtek ALC285'
   Components : 'HDA:10ec0285,17aa225c,00100002 HDA:8086280b,80860101,00100000'
   Controls : 53
   Simple ctrls : 15
Card1.Amixer.info:
 Card hw:1 'Audio'/'Generic ThinkPad Dock USB Audio at usb-0000:00:14.0-4.2.4, high speed'
   Mixer name : 'USB Mixer'
   Components : 'USB17ef:306f'
   Controls : 9
   Simple ctrls : 4
Channel: Unavailable
Date: Sat Feb 22 05:41:10 2020
ForcedLayersAccel: False
IncompatibleExtensions:
 Pentadactyl - <email address hidden>
 English (GB) Language Pack - <email address hidden>
 English (South Africa) Language Pack - <email address hidden>
 Default - {972ce4c6-7e08-4474-a285-3208198ce6fd}
IpRoute:
 default via 192.168.0.1 dev enp0s31f6 proto dhcp metric 100
 10.23.231.0/24 dev lxdbr0 proto kernel scope link src 10.23.231.1
 192.168.0.0/24 dev enp0s31f6 proto kernel scope link src 192.168.0.34 metric 100
 192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown
MostRecentCrashID: bp-ea952d4d-f25a-4ced-893c-8cabb2160112
PrefErrors: Unexpected character ',' before close parenthesis @ /usr/lib/firefox/omni.ja:greprefs.js:737
PrefSources: prefs.js
ProcEnviron:
 TERM=rxvt-unicode-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
Profiles: Profile0 (Default) - LastVersion=73.0.1/20200217142647 (In use)
RunningIncompatibleAddons: True
SourcePackage: firefox
UpgradeStatus: Upgraded to focal on 2020-01-24 (28 days ago)
dmi.bios.date: 11/25/2019
dmi.bios.vendor: LENOVO
dmi.bios.version: N23ET69W (1.44 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20KHCTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40709 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrN23ET69W(1.44):bd11/25/2019:svnLENOVO:pn20KHCTO1WW:pvrThinkPadX1Carbon6th:rvnLENOVO:rn20KHCTO1WW:rvrSDK0J40709WIN:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad X1 Carbon 6th
dmi.product.name: 20KHCTO1WW
dmi.product.sku: LENOVO_MT_20KH_BU_Think_FM_ThinkPad X1 Carbon 6th
dmi.product.version: ThinkPad X1 Carbon 6th
dmi.sys.vendor: LENOVO