firefox fullscreen display glitches with hidpi scalingb

When I go on fullscreen on a video on Firefox with HIDPI scaling factors more than 100%, I get odd behavior of the fullscreen video. This behavior is not seen on Chrome, or if the scaling factor is 100%.

Basically, it seems like there is some resizing of the video to a smaller window in the upper left, and when I escape fullscreen, sometimes the firefox window itself is scaled off the display.

At times, this glitches a few times and eventually resets, sometimes, it stays this way. It appears to have changed behavior multiple times over the past few weeks of updates of various parts of the stack, and may just be narrowed down for me now to something repeatable. For instance sometimes I could not trigger it until I pressed volume up or volume down. Now it appears to happen just waiting for a few seconds on the running video.

This is on X11, and on focal with the latest updates as of today 2020-04-01.

Happy to debug more, not sure what information is useful.

thanks!

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: firefox 74.0+build3-0ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-21.25-generic 5.4.27
Uname: Linux 5.4.0-21-generic x86_64
AddonCompatCheckDisabled: False
ApportVersion: 2.20.11-0ubuntu21
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: dpb 1522 F.... pulseaudio
BuildID: 20200309095159
Channel: Unavailable
CurrentDesktop: ubuntu:GNOME
Date: Wed Apr 1 21:12:08 2020
DefaultProfileExtensions: extensions.sqlite corrupt or missing
DefaultProfileIncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
DefaultProfileLocales: extensions.sqlite corrupt or missing
DefaultProfilePrefErrors: Unexpected character ',' before close parenthesis @ /usr/lib/firefox/omni.ja:greprefs.js:729
DefaultProfileThemes: extensions.sqlite corrupt or missing
ForcedLayersAccel: False
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2020-02-22 (39 days ago)
InstallationMedia: Ubuntu 18.04.4 LTS "Bionic Beaver" - Release amd64 (20200203.1)
IpRoute:
 default via 10.10.0.1 dev wlp4s0 proto dhcp metric 600
 10.10.0.0/16 dev wlp4s0 proto kernel scope link src 10.10.1.4 metric 600
 169.254.0.0/16 dev wlp4s0 scope link metric 1000
ProcEnviron:
 TERM=screen-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
Profile0Extensions: extensions.sqlite corrupt or missing
Profile0IncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
Profile0Locales: extensions.sqlite corrupt or missing
Profile0PrefErrors: Unexpected character ',' before close parenthesis @ /usr/lib/firefox/omni.ja:greprefs.js:729
Profile0PrefSources: prefs.js
Profile0Themes: extensions.sqlite corrupt or missing
Profiles:
 Profile1 (Default) - LastVersion=None/None (Out of date)
 Profile0 - LastVersion=74.0/20200309095159
RunningIncompatibleAddons: False
SourcePackage: firefox
UpgradeStatus: Upgraded to focal on 2020-02-22 (39 days ago)
dmi.bios.date: 11/25/2019
dmi.bios.vendor: LENOVO
dmi.bios.version: N1MET59W (1.44 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20HRCTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: Not Defined
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrN1MET59W(1.44):bd11/25/2019:svnLENOVO:pn20HRCTO1WW:pvrThinkPadX1Carbon5th:rvnLENOVO:rn20HRCTO1WW:rvrNotDefined:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad X1 Carbon 5th
dmi.product.name: 20HRCTO1WW
dmi.product.sku: LENOVO_MT_20HR_BU_Think_FM_ThinkPad X1 Carbon 5th
dmi.product.version: ThinkPad X1 Carbon 5th
dmi.sys.vendor: LENOVO